AWWA Water Treatment & Distribution Definitions Grade 1

A US government agency responsible for implementing federal laws designed to protect the environment.

US Environmental Protection Agency
(USEPA)

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Anything found in water other than water itself.

Contaminant

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A disease-causing organism.

Pathogen

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An organism too small to be seen by the naked eye and visible only with a microscope.

Microorganism

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An organism that lives within, and may cause harm, to other organisms.

Parasite

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A one-celled microscopic organism that has no chlorophyll.

Usually has a spherical, rodlike, or curved shape.

Bacteria

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A bacterium of the coliform group used as a substitute for fecal coliforms in the regulations of the Total Coliform Rule.

Escherichia coli (E. coli)

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A porous layer of paper, glass fiber, or cellulose acetate used to remove particulate matter from water samples and other chemical solutions.

Filter

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The smallest and simplest form of life.

Virus

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Small single-celled animals including amoebae, ciliates, and flagellates.

Protozoa

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A protozoan that can survive in water that causes human disease.

Giardia

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A group of bacteria predominately inhabiting the intestines of humans or animals, but occasionally found elsewhere.

Coliform Bacteria

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A laboratory method used for coliform testing that uses a nutrient broth placed in tubes.

Multiple-Tube Fermentation (MTF) Method

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An approved bacteriological procedure for the detection of fecal coliforms.

Used for the rapid detection of E. coli through visual fluorescence when viewed under a UV light.

MNO-MUG Method

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An approved bacteriological method for the detection of total coliforms.

This is a simple way to determine if coliform bacteria is present or absent.

Presence-Absence (P-A) Method

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A laboratory method used to detect bacteria by capturing them on a membrane filter.

Membrane Filter (MF) Method

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A regulation that became effective after December 31, 1990, doing away with the previous maximum contaminant level (MCL) relating to the density of organisms and relating only to the presence or absence of the organisms in water.

Total Coliform Rule

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A laboratory method used to estimate the bacteria population present in water (by culturing them on a specific agar).

Heterotrophic Plate Count (HPC)

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The smallest particle of an element that still retains the characteristics of that element.

Atom

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One of the tree elementary particles of an atom (along with neutrons and electrons).

A positively charged particle located in the nucleus of an atom.

Proton

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An uncharged elementary particle that has a mass approximately equal to that of the proton.

These are present in all atomic nuclei (except in the lightest hydrogen nucleus).

Neutron

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One of the three elementary particles of an atom (along with protons and neutrons).

A tiny, negatively charged particle that orbits around the nucleus of an atom.

Electron

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The center of an atom, made up of positively charged particles called protons and uncharged particles called neutrons.

Nucleus

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The number of protons in the nucleus of an atom.

Atomic Number

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The sum of the number of protons and the number of neutrons in the nucleus of an atom.

Atomic Weight

An atom of the same element, but containing varying numbers of neutrons in the nucleus. Stable ones do not emit radiation and Unstable ones do emit radiation.

Isotope

An atom that is electrically unstable because it has more or fewer electrons than protons. This atom carries either a positive or an negative charge resulting from the loss or gain of electrons.

Ion

A positively charged ion..

Cation

A negatively charged ion.

Anion

A chart showing all the elements arranged according to similarities of chemical properties.

Periodic Table

The standard abbreviation, either one or two letters, of an element.

Chemical Symbol

Anything that occupies space and has weight (mass).

Matter

Two or more elements joined together by a chemical bond.

Compound

Two or more atoms joined together by a chemical bond.

Molecule

An electron in the outermost electron shell.

Valence Electron

Two or more elements, compounds, or both, mixed together with no chemical reaction (bonding).

Mixture

A group of elements chemically bonded together and acting like single atoms or ions in their ability to form other compounds.

Polyatomic Ion

Using the chemical symbols for each element, a shorthand way of writing that elements and how many elements of each are present.

Chemical Formula

The proportion, calculated as a percentage, of each element in a compound.

Percent by Weight

The sum of all of the atomic weights of all atoms in a compound.

Molecular Weight

A shorthand way, using chemical formulas, of writing the reaction that takes place when chemicals are brought together; with reactants on the left and products on the right of an arrow indicating the direction of the reaction.

Chemical Equation

A liquid containing a dissolved substance.

Solution

The liquid used to dissolve a substance.

Solvent

The substance dissolved in a solution.

Solute

In chemistry, a measurement of how much solute is contained in a given amount of solution, commonly measured in milligrams per liter (mg/L).

Concentration

A chemical substance of mineral origin not having carbon in its molecular structure.

Inorganic Compound

Any substance that releases hydrogen ions (H+) when mixed into water.

Acid

Any substance that produces hydroxide ions when it dissociates in water.

Base

A measurement of how acidic or basic a substance is, from 0 (most acidic) to 14 (most basic). A measurement of 7 indicates that the substance is neutral.

A measurement of water's ability to neutralize an acid.

Alkalinity

A chemical substance of animal or vegetable origin having carbon in its molecular structure.

Organic Compound

Disinfection byproduct compounds formed by the reaction of organic material in water with chlorine or other disinfectants, consisting of chloroform, bromoform, dichloromethane, and dibromochloromethane.

Trihalomethanes (THMs)

The maximum permissible level of a contaminant in water as specified in the regulations of the Safe Drinking Water Act.

Maximum Contaminant Level (MCL)

Chemicals formed as a reaction of disinfectants with contaminants in water, consisting of monochloroacetic acid, dichloroacetic acid, trichloroacetic acid, monobromoacetic acid, and dibromoacetic acid.

Haloacetic Acids (HAA5s)

A chemical produced by humans that can contaminate water.

Synthetic Organic Chemical (SOC)

Non-enforceable health-based goals published along with the promulgation of an MCL.

Maximum Contaminant Level Goal (MCLG)

Behavior of a material that has an unstable atomic nucleus, which spontaneously decays or disintegrates, producing radiation.

Radioactivity

The quantity of radiation (other than X-rays or other generated radiation) that produces in one gram of human tissue ionization equivalent to the quantity produced in air by one roentgen of radiation or X-rays (equivalent to 83.8 ergs of energy).

Roentgen Equivalent Physical (rep)

A measure of the dose absorbed by the body from radiation (100 ergs of energy in 1 gram of tissue).

Radiation Absorption Dose (rad)

A quantification of radiation in terms of its dose effect on the human body; the number of rads times a quality factor).

Roentgen Equivalent Man (rem)

A method which any number can be expressed as a number between 1 and 9 multiplied by a power of 10.

Scientific Notation

A relationship between two numbers. This may be expressed using colons (for example, 1:2 or 3:7), or it may be expressed as a fraction (for example, 1/2 or 3/7).

Ratio

The relationship between two numbers in a ratio. When it is the same as that between two other numbers in another ratio, the two ratios are to be in proportion, or proportionate.

Proportion

A method to group information so that trends in the information may be determined.

Average

A measurement of average value, calculated by summing all terms and dividing by the number of terms.

Arithmetic Mean

The fraction of the whole expressed as parts per one hundred.

Percent

A supply of piped water for human consumption that has at least 15 service connections, or serves 25 or more people 60 or more days each year.

Public Water System (PWS)

A new chemical compound formed by the reaction of disinfectants with organic compounds in water. At high concentrations, many of these are considered a danger to human health.

Disinfection By-Products (DBPs)

The product of a residual disinfectant concentration C, in milligrams per liter, and the corresponding disinfectant contact time T, in minutes. Minimum values are specified by the Surface Water Treatment Rule as a means of ensuring adequate kill or inactivation of pathogenic microorganisms in water.

C x T Value

The science of dealing with the properties, distribution, and circulation of water in the atmosphere, on and below the earth's surface.

Hydrology

The movement of water to and from the surfaces of the earth.

Hydrologic Cycle

Water that moves off land and water surfaces and into the atmosphere.

Evaporation

The release of water into the air by plants, primarily through their leaves.

Transpiration

Water movement with the air currents in the atmosphere.

Advection

Water vapor in the air formed by tiny droplets.

Condensation

Water that falls out of the atmosphere as rain, snow, or ice.

Precipitation

The process of rain water landing on vegetation, not reaching the ground.

Interception

The process of rain water reaching the ground and soaking through the soil.

Infiltration

Water movement below the surface, influenced by gravity and the presence of natural barriers in the rock or soil.

Subsurface Flow

Water that reaches the ground and flows towards nearby water bodies.

Runoff

Runoff that flows into small channels that feeds into larger channels that carry rivers and streams.

Channel Flow

The removal of water from circulation because it is frozen, held in a lake above-ground, or held in an aquifer below-ground.

Storage

Water that has collected as snow or ice and been released as liquid.

Snowmelt

Subsurface water occupying the saturation zone, from which wells and springs are fed. In a strict sense, the term only applies to water below the water table.

Groundwater

A porous, water-bearing geologic formation. Generally restricted to materials capable of yielding an appreciable supply of water.

Aquifer

An indication of the volume of space within a given amount of material.

Porosity

The characteristic of how easily water will flow through a material.

Permeability

A location where groundwater emerges on the surface of the ground.

Spring

All water on the surface, as distinguished from groundwater.

Surface Water

An area from which surface runoff is carried away by a single drainage system. Also called a catchment area, watershed, or watershed drainage area.

Drainage Basin

Pleasing to the taste.

Palatable

A well feature that prevents contamination from entering the well.

Sanitary Seal

The metal pipe used to line the borehole of a well.

Well Casing

A well feature that prevents rock and soil from entering the well, while letting water in.

Well Screen

A concrete area placed around the casing of some wells to support pumping equipment and to help prevent surface water from contaminating the well water.

Well Slab

The level of water in a well when no water is being taken from the aquifer.

Static Water Level

The upper surface of the zone of saturation, closest to the ground surface.

Water Table

The difference between the static water level and the pumping level in a well.

Drawdown

The cone-shaped depression on the groundwater level around a well during pumping.

Cone of Depression

The rate of water withdrawal that a well can supply over a long period of time.

Well Yield

A well's pumping rate divided by the drawdown level.

Specific Capacity

A very wide, relatively shallow caisson that has horizontally drilled wells with screen points at the bottom. These wells are large producers.

Radial Wells

A sub surface structure to receive water filtered through a streambed.

Infiltration Gallery

A pond, lake, or reservoir constructed by carving out a basin or building a dam across a stream valley.

Impoundment

The addition of water to the groundwater supply from precipitation and by infiltration from the surface streams, lakes, reservoirs, and snowmelt.

Recharge

A structure or device placed in a surface water source to permit the withdrawal of water from that source.

Intake Structure

The accumulation of silt in an impoundment.

Siltation

The separation of water in lakes and reservoirs such that a warm layer of water overlies a cooler layer.

Stratification

The upper, warmer layer of water in a stratified lake.

Epilimnion

The lower layer of water in a stratified lake. The water temperature is near 39.2 degrees F (4 degrees C), at which water attains its maximum density.

Hypolimnion

The temperature transition zone in a stratified lake, located between the epilimnion and the hypolimnion.

Thermocline

Use of a method to prevent to prevent a lake or reservoir from becoming stratified. Typically consists of releasing diffused compressed air at a low point on the lake bottom.

Destratification

A pretreatment method that uses course screens to remove large debris from water to prevent clogging of pipes or channels to the treatment plant.

Screening

A series of straight steel bars, welded at their ends to horizontal steel beams, forming a grid. These are placed on intakes or in waterways to remove large debris.

Bar Screens

A screen made of a wire fabric attached to a metal frame. The screen is usually equipped with a motor so that it can move continuously through the water and be automatically cleaned with a water spray. It is used to remove finer debris from the water than a bar screen is able to remove.

Wire-Mesh Screen

A preliminary treatment process used to remove gravel, sand, and other gritty material from the raw water before it enters the main treatment plant. This is usually done without the use of coagulation chemicals.

Presedimentation

An enlargement of a conduit carrying the raw water that allows the water velocity to slow down so that sand and other grit can settle.

Sand Trap

A centrifugal sand-and-grit removal device.

Cyclone Degritter

A rotating drum lined with a finely woven material, such as stainless steel. These are used to remove algae and small debris before they enter the treatment plant.

Microstrainer

Source water oxidation with hypochlorite or ozone.

Preoxidation

Finely divided solids, such as bacteria and fine clay particles, that will stay suspended in water for long periods of time.

Nonsettleable Solids

A physical characteristic of water making the water appear cloudy. The condition is caused by the presence of suspended matter.

Turbidity

The water treatment process that causes very small particles to attract one another to form larger particles. This is accomplished by the addition of a chemical that neutralizes the electrostatic charges on the particles that causes them to repel each other.

Coagulation

A term that describes the treatment process used by most US surface water systems consisting of the steps of coagulation, flocculation, sedimentation, and filtration.

Conventional Treatment

The water treatment process, following coagulation, that uses gentle stirring to bring suspended particles together so that they can form larger, more settleable clumps, called floc.

Flocculation

Collections of the smaller particles (such as silt, organic matter, and microorganisms) that have come together (agglomerated) into larger, more settleable particles as a result of the coagulation-flocculation process.

Floc

A solid organic or inorganic particle that is held in suspension by the action of flowing water.

Suspended Solid

A denser and heavier suspended solid that will settle unaided to the bottom of a sedimentation basin within 4 hours.

Settleable Solid

A finely divided solid that will not settle out of water for very long periods of time unless the coagulation-flocculation process is used.

Colloidal Solid

Any material that is dissolved in water and can be recovered by evaporating the water after filtering the suspended material.

Dissolved Solid

The accumulated solids separated from water during treatment.

Sludge

A coagulant aid used to form denser, stronger floc.

Activated Silica

A material, such as bentonite clay, added to low-turbidity waters to provide additional particles for good floc formation.

Weighting Agent

A high-molecular weight, synthetic organic compound that forms ions when dissolved in water. Also called a polymer.

Polyelectrolyte

A process of quickly mixing a chemical solution uniformly through the water.

Rapid Mixing

A device designed to produce turbulence and mixing of chemicals with water, by means of fixed sloping vanes within the unit, without the need for any application of power.

Static Mixing

The water treatment process that involves reducing the velocity of water in basins so that the suspended material can settle out by gravity.

Sedimentation

A basin or tank in which water is retained to allow settleable matter, such as floc, to settle by gravity. Also called a settling basin, settling tank, or a sedimentation tank.

Sedimentation Basin

Water flowing into a basin.

Influent

Water flowing from a basin.

Effluent

Uniform flow in a horizontal direction.

Rectilinear Flow

Flow that moves across a basin from the center to the outside edges, or visa versa.

Radial Flow

A trough that collects the water flowing from a basin (effluent) and transports it to the effluent piping system.

Launder

The water treatment process involving the removal of suspended matter by passing the water through a porous medium, such as sand.

Filtration

Granular material through which material is collected and stored when water passes through it.

Filter Media

A filtration method that includes coagulation, flocculation, and filtration, but excludes sedimentation. Only applicable to raw water relatively low in turbidity because all suspended matter must be trapped by the filters.

Direct Filtration

A filtration process that involves passing raw water through a bed of sand at low velocity, resulting in particulate removal by physical and biological mechanisms.

Slow Sand Filtration

A pressure filter using a medium made from diatoms. The water is forced through the filter medium by pumping.

Diatomaceous Earth Filter

A small, prefabricated unit that has been designed and assembled at a factory and then shipped to the installation site.

Package Treatment Plant

The layer of solids and biological growth that forms on top of a slow sand filter, allowing the filter to remove turbidity effectively without chemical coagulation.

Schmutzdecke

The water treatment process that kills disease-causing organisms in water, usually by the addition of chlorine.

Disinfection

A disease caused by a waterborne organism or toxic substance.

Waterborne Disease

A container that holds 150 lb (68kg) of chlorine and has a total filled weight of 250-285 lb (110-130 kg).

Chlorine Cylinder

A reusable, welded tank that holds 2,000 lb (910 kg) of chlorine. These tanks weigh about 3,700 lb (1,700 kg) when full and are generally 30 in. (0.76 m) in diameter and 80 in. (2.03 m) long.

Ton Container

Any device that is used to add chlorine to water.

Chlorinator

The portion of the chlorination system that feeds the chlorine solution into a pipe, under pressure.

Injector

A section of perforated pipe or porous plates used to inject gas, such as carbon dioxide or air, under pressure into water.

Diffuser

A heating device used to convert liquid chlorine to chlorine gas.

Chlorine Evaporator

Chlorination using solutions of calcium hypochlorite or sodium hypochlorite.

Hypochlorination

An abundant element found naturally in the earth; as a result, it is found dissolved in most water supplies. When the concentrations exceed 0.3 mg/L, it causes red stains on plumbing fixtures and other items in contact with the water. It can be found dissolved in water as a result of the corrosion of cast-iron or steel pipes. This is usually that cause of red-water problems.

Iron

An abundant element found naturally in the earth; it is found dissolved in many water supplies. At concentrations above 0.05 mg/L, it causes black stains on plumbing fixtures, laundry, and other items in contact with the water.

Manganese

An ion from the element fluorine. It is a constituent of the earth's crust and consequently is found naturally, to some degree, in all drinking water sources. A small amount of this in the diet is essential for proper bone and tooth formation.

Fluoride

The water treatment process in which a chemical is added to the water to increase the concentration of fluoride ions to an optimal level. The purpose of adding this is to reduce the incidence of dental cavities in children.

Fluoridation

Staining or pitting of the teeth due to excessive amounts of fluoride in the water.

Fluorosis

A dry chemical used in the fluoridation of drinking water. It is commonly used in saturators.

Sodium Fluoride

A strongly acidic liquid used to fluoridate drinking water.

Fluorosilicic Acid

A dry chemical used in the fluoridation of drinking water. It is derived from fluorosilicic acid.

Sodium Fluorosilicate

A sample containing all of the constituents that are in the water from which it was taken.

Representative Sample

A single water sample collected at one time from a single point.

Grab Sample

A series of individual or grab samples taken at different times from the same sampling point and mixed together.

Composite Sample

A plan for laboratory operation that specifies the measures used to produce data of known precision and bias.

Quality Assurance (QA)

A laboratory program of continually checking techniques and calibrating instruments to enable consistency in analytical results.

Quality Control (QC)

A written record of a sample's history of SDWA compliance, from the time of collection to the time of analysis and subsequent disposal.

Chain of Custody

The oxygen dissolved in water, wastewater, or other liquid, usually expressed in milligrams per liter, parts per million, or percent of saturation.

Dissolved Oxygen

The gradual degradation or destruction of a substance or material by chemical action. The action proceeds inward from the surface.

Corrosion

Mineral deposits left in pipelines and plumbing fixtures.

Scaling

A knob of rust formed on the interior of cast-iron pipes as a result of corrosion.

Tubercle

The water treatment process intended to reduce the corrosive or scale-forming tendencies of water.

Stabilization

Rust-colored water resulting from the formation of ferric hydroxide from iron naturally dissolved in that water or from the action of iron bacteria.

Red Water

A form of localized corrosion that can form deep pits and tubercles.

Concentration Cell Corrosion

A form of localized corrosion caused by the connection of dissimilar metals in an electrolyte, such as water.

Galvanic Corrosion

The point at which water can no longer dissolve any more of a particular chemical. Precipitation of the chemical will happen after this point.

Saturation Point

A characteristic of water, caused primarily by the salts of calcium and magnesium. This causes deposition of scale in boilers, damage in some industrial processes, and sometimes questionable taste.

Hardness

The water treatment process that removes calcium and magnesium, the hardness-causing constituents in water.

Softening

A precipitation process used to remove hardness from water.

Lime-Soda Ash Process

A chemical substance of animal or vegetable origin, having carbon in its molecular structure.

Organic Compound

The water treatment process used primarily to remove organic contaminants from water. This involves the adhesion of the contaminants to an adsorbent, such as activated carbon.

Adsorption

The process of bringing water and air into close contact to remove or modify constituents in water.

Aeration

A means of dissolving air into water (aeration) wherein water is distributed over the packing at the top of a tank and air is forced in at the bottom using a blower. Also called Desorption.

Air Stripping

A common gas in the atmosphere that is very soluble in water. High concentrations in water can cause the water to be corrosive. This gas is added to water after the lime-softening process to lower the pH in order to reduce calcium carbonate scale formation. -This process is called Recarbonization.

Carbon Dioxide (CO2)

A toxic gas produced by anerobic decomposition of organic matter and by sulfate-reducing bacteria. This gas has a very noticeable "rotten egg" odor.

Hydrogen Sulfide (H2S)

A colorless, odorless, flammable gas formed by the anaerobic decomposition of organic matter. When dissolved in water, it causes a garlic-like taste. Also called "Swamp Gas."

Methane (CH4)

A manufactured, synthetic chemical generally used as an industrial solvent. These are classified as known or suspected carcinogens, or as causing other health effects. They are of particular concern to the water supply industry because they have widely been found as contaminants in groundwater sources.

Volatile Organic Chemical (VOC)

A pressure-driven process in which almost-pure water is passed through a semipermeable membrane. Water is forced through the membrane and most ions (salts) are left behind. This process is primarily used for desalination of seawater.

Reverse Osmosis (RO)

A process in which ions are transferred through a membrane as a result of a direct electric current being applied to the solution.

Electrodialysis

A process used to remove hardness from water that depends on special materials known as resins. The resins trade nonhardness-causing ions (usually sodium) for the hardness-causing ions, calcium and magnesium. The process practically removes all of the hardness from water.

Ion Exchange

An excess of chemical left in water after treatment. The presence of this in water after treatment indicates that an adequate amount of disinfectant has been added at the treatment stage to ensure completion of all reactions with some disinfectant remaining.

Residual

The study of the combined effects of electricity and magnetism.

Electromagnetics

A state in which electrons have accumulated but, are not flowing from one position to another. This is also referred to as "electricity at rest."

Static Electricity

Electrical current that flows continuously in one direction.

Direct Current (DC)

Electrical current that reverses direction in a periodic manner.

Alternating Current (AC)

The general class of pumps that sue a rapidly turning impeller to impart kinetic energy or velocity to fluids. The pump casing then converts this velocity head, in part, to pressure head. Also called a "Kinetic Pump."

Velocity Pump

The rotating set of vanes that forces water through a pump.

Impeller

(1) A measure of the energy possessed by water at a given location in the water system, expressed in feet (or meters). (2) A measure of the pressure (force) exerted by water, expressed in feet (or meters).

Head (Pressure)

(1) In a pump, the percentage of water taken into the suction end that is not discharged because of clearances in the moving unit. (2) In a motor, the difference between the speed of the rotating magnetic field produced by the stator and the speed of the rotor.

Slip

A pump consisting of an impeller on a rotating shaft enclosed by a casing that has suction and discharge connections. The spinning impeller throws waster outward at a high velocity, and the casing shape converts this high velocity to a high pressure.

Centrifugal Pump

A centrifugal pump, commonly of the multistage diffuser type, in which the pump shaft is mounted vertically.

Vertical Turbine Pump

A type of positive-displacement pump consisting of a closed cylinder containing a piston or plunger to draw liquid into the cylinder through an inlet valve and force it out through an outlet valve. When the piston acts on the liquid in one end of the cylinder, the pump is termed to be "Single-Action;" when the piston acts in both ends, the pump is termed to be "Double-Action."

Reciprocating Pump

A type of positive-displacement pump consisting of elements resembling gears that rotate in a close-fitting pump case. The rotation of these elements alternately draws in and discharges the water being pumped. Such pumps act with neither suction nor discharge valves, operate at almost any speed, and do not depend on centrifugal forces to lift water.

Rotary Pump

A centrifugal pump in which water enters from only one side of the impeller. Also called an "End-Suction Pump."

Single-Suction Pump

A centrifugal pump in which the water enters from both sides of the impeller. Also called a "Split-Case Pump."

Double-Suction Pump

A product description listing a chemical's identity, composition, and type or types; the hazard(s) associated with its use (is it flammable, an oxidizer, poisonous?); how it enters the body; the effects of exposure; health effects (shot term, long term); the permissible exposure limit; how to handle spills or releases; and other related information.

Material Safety Data Sheet (MSDS) or Safety Data Sheet (SDS)

A type of respirator that supplies safe, grade D (or better) breathing air to the wearer.

Self-Contained Breathing Apparatus (SCBA)

Activated carbon in a fine powder form. It is added to water in a slurry form primarily for removing those compounds causing tastes and odors.

Powdered Activated Carbon (PAC)

Activated carbon in a granular form, which is used in a bed, much like a conventional filter, to adsorb organic substances from water.

Granular Activated Carbon (GAC)

Using the chemical symbols for each element, a shorthand way of writing what elements are present in a molecule and how many atoms of each element are present in each of the molecules.

Chemical Formula

The proportion calculated as a percentage, of each molecule in a compound.

Percent by Weight

The sum of the atomic weights of all the atoms in the compound. Also called "Formula Weight."

Molecular Weight

A shorthand way, using chemical formulas, of writing the reaction that takes place when chemicals are brought together. The left side of the equation indicates the chemicals brought together (reactants); the arrow indicates in which direction the reaction occurs; and the right side of the equation indicates the results (the products) of the chemical reaction.

Chemical Equation

An indication of the relative number of molecules of the compound that are involved in the chemical reaction.

Coefficient

The quantity of a compound or element that has a weight in grams equal to the other substance molecular or atomic weight.

Mole

The weight of a compound that contains one equivalent of a hydrogen (for acids) or one equivalent of a hydroxide (for bases). This is calculated by dividing the molecular weight of a compound by the number of H+ or OH- present in the compound.

Equivalent Weight

The number of equivalent weights of solute per liter of solution.

Normality

A liquid containing a dissolved substance. The liquid alone is called the solvent and the dissolved substance is called the solute.

Solution

In chemistry, a measurement of how much solute is contained in a given amount of solution. These are commonly measured in milligrams per liter (mg/L).

Concentration

A measurement of the amount of treated water by a plant each day. It is the average of the daily flows that occur within a period of time, such as a week, a month, or a year. Mathematically, it is the sum of all daily flows divided by the total number of daily flows used.

Average Daily Flow (ADF)

A measurement of the amount of water leaving a sedimentation basin per unit of basin surface area. Mathematically, it is the flow rate from the basin divided by the basin surface area.

Surface Overflow Rate

A measurement of the volume of water applied to each unit of filter surface area. Mathematically, it is the flow rate into the filter divided by the total filter area.

Filter Loading Rate

A measurement of the volume of water flowing upward (backwards) through a unit of filter surface area. Mathematically, it is the gallons of backwash water divided by the total filter area.

Filter Backwash Rate

An accumulation of media grains and suspended material that creates clogging problems in filters.

Mudball

The average length of time that a drop of water or a suspended particle remains in a tank or basin. Mathematically, its the volume of water in the tank divided by the amount of water through the tank. The units of flow rate in this calculation are dependent of whether the time is calculated in minutes, hours, or days.

Detention Time

The force pushing on a unit of area. Normally it is measured in pascals (Pa), pounds per square inch (psi), or feet of head.

Pressure

A measure of pressure per unit of space.

Pounds per Square Inch (psi)

(1) A measure of the energy possessed by water at a given location in the water system, expressed in feet (or meters). (2) A measure of pressure (force) exerted by water, expressed in feet (or meters).

Head (Pressure)

The water pressure as measured by a gauge, expressed as "psig." This is not total pressure; total pressure (absolute pressure) also includes the atmospheric pressure (about 14.7 psi at sea level)exerted on the water. However, because atmospheric pressure is exerted everywhere (against the outside of the main as well as the inside, for example), it is generally not written into water system calculations.

Gauge Pressure

The total pressure in a system, including both the pressure of the water and the pressure of the atmosphere (about 14.7 psi, at sea level).

Absolute Pressure

Pressure measured by a gauge and expressed in terms of pounds per square inch.

Pounds per Square Inch Gauge (psig)

A flow rate of water measured at one particular instant, such as by a metering device, involving a cross-sectional area of the channel or pipe and the velocity of the water at that instant.

Instantaneous Flow Rate

The average of the instantaneous flow rates over a given period of time, such as a day.

Average Flow Rate

A US government agency responsible for implementing federal laws designed to protect the environment. Congress has delegated implementation of the Safe Drinking Water Act to this agency.

US Environmental Protection Agency (USEPA)

Nonenforceable health-based goals published along with the promulgation of an MCL. Originally called Recommended Maximum Contaminant Levels (RMCLs).

Maximum Contaminant Level Goal (MCLG)

The maximum permissible level of a contaminant in water as specified in the regulations of the Safe Drinking Water Act (SDWA).

Maximum Contaminant Level (MCL)

A new chemical compound formed by the reaction of disinfectants with organic compounds in water. At high concentrations, many of these are considered a danger to human health.

Disinfection By-Product (DBP)

The average of four quarterly samples at each monitoring location to ensure compliance with the Stage 1 Disinfection By-Product Rule (DBPR).

Running Annual Average (RAA)

The product of the residual disinfectant concentration C, in milligrams per liter, and the corresponding disinfectant contact time T, in minutes. Minimum values are specified by the Surface Water Treatment Rule as a means of ensuring adequate kill or inactivation of pathogenic microorganisms in water.

C x T Value

The water treatment process that causes very small suspended particles to attract one another and form larger particles. This is accomplished by the addition of a chemical that neutralizes the electrostatic charges on the particles that causes them to repel each other.

Coagulation

The water treatment process, following coagulation, that uses gentle stirring to bring suspended particles together so that they will form larger, more settleable clumps, called floc.

Flocculation

A measurement of how acidic or basic a substance is. The scale runs from 0 (most acidic) to 14 (most basic), with 7 being neutral.

A measurement of a water's ability to neutralize an acid.

Alkalinity

A physical characteristic of water making it appear cloudy. This condition is caused by the presence of suspended matter.

Turbidity

The amount of carbon bound in organic compounds in a water sample as determined by a standard laboratory test.

Total Organic Carbon (TOC)

A test that determines humic content by measuring the absorbance of UV light at 254 nm and divides that value by the dissolved organic carbon concentration.

Specific Ultraviolet Absorbance (SUVA)

The water treatment process that involves reducing the velocity of water in basins so that the suspended material can settle out by gravity.

Sedimentation

A basin or tank in which water is retained to allow settleable matter, such as floc, to settle by gravity. Also called a settling basin, settling tank, or a sedimentation tank.

Sedimentation Basin

Water flowing into a basin.

Influent

Water flowing from a basin.

Effluent

The accumulated solids separated from water during treatment.

Sludge

Uniform water flow in a horizontal direction.

Rectilinear Flow

Flow that moves across a basin from the center to the outside or vice versa.

Radial Flow

A basin in which the coagulation, flocculation, and sedimentation processes are combined. The water flows upward through the basin. It is primarily used in the lime softening of water. It can also be called an upflow clarifier or sludge-blanket clarifier.

Solids-Contact Basin

A clarification process in which gas bubbles are generated in a basin so that they will attach to solid particles, causing them to rise to the surface. The sludge that accumulates on the surface is then periodically removed by flooding or mechanical scraping.

Dissolved-Air Flotation (DAF)

The concrete or steel basin that contains the filter media, gravel support bed, underdrain. and wash water troughs.

Filter Tank

Granular material through which material is collected and stored when water passes through it.

Filter Media

A filter underdrain system using a main pipe (header) with several smaller perforated pipes (laterals) branching from it on both sides.

Pipe Lateral Collector

A patented underdrain system using small porcelain spheres of various sizes in conical depressions.

Wheeler Filter Bottom

A trough placed above the filter media to collect the backwash water and carry it to the drainage system.

Wash-Water Trough

The practice of admitting air through the underdrain system to ensure complete cleaning of the filter media during a normal filter backwash. Normally, this is an alternative to using a surface wash system.

Air Scouring

A control valve used to maintain a fairly constant flow through the filter.

Rate-of-Flow Controller

A device that measures turbidity, the amount of suspended particulate matter in water.

Turbidimeter

Collections of smaller particles (such as silt, organic matter, and microorganisms) that have come together (agglomerated) into larger, more settleable particles as a result of the coagulation-flocculation process.

Floc

High-molecular weight, synthetic organic compound that is used to aid in the coagulation and flocculation process.

Polymer

A measurement (in millivolts) of the particle charge strength surrounding colloidal solids. The more negative the number, the stronger the particle charge and repelling force between particles.

Zeta Potential

A violent washing action in a filter caused by uneven distribution of backwash water.

Sand Boil

A condition that occurs in filters when air comes out of solution as a result of pressure decreases and temperature increases. The air clogs the voids between the media grains, which causes increased head loss through the filter and shorter filter runs.

Air Binding

A pressure filter using medium made from diatoms. The water is forced through the medium by pumping.

Diatomaceous Earth Filter

A container that holds 150 lbs (68 kg) of chlorine and has a total filled weight of 250-285 lbs (110-130 kg).

Chlorine Cylinder

A reusable, welded tank that holds 2,000 lbs (910 kg of chlorine. These tanks weigh about 3,700 lbs (1,700 kg) when full and are generally 30 in. (0.75 m) in diameter and 80 in (2.03 m) long.

Ton Container

Any device that is used to add chlorine to water.

Chlorinator

The portion of a chlorination system that feeds the chlorine solution into a pipe under pressure.

Injector

A section of perforated pipe r porous plates used to inject gas, such as carbon dioxide or air, under pressure into water.

Diffuser

Chlorination using solutions of calcium hypochlorite or sodium hypochlorite.

Hypochlorination

An abundant element found naturally in the earth; as a result it is found dissolved in most water supplies. When the concentration exceeds 0.3 mg/L, it causes red stains on plumbing fixtures and other items in contact with the water. This can also be found, dissolved in water as a result of corrosion of cast-iron or steel pipes. This is usually the cause of red-water problems.

Iron

An abundant element found naturally in the earth and dissolved in many water supplies. At a concentration of 0.05 mg/L, it causes black stains on plumbing fixtures, laundry, and other items in contact with the water.

Manganese

Materials used to filter raw water, including granular media, sand, crushed quartz, garnet sand, manganese greensand, and filter coal.

Granular Filter Media

A piece of equipment that feeds a sodium fluoride solution into water for fluoridation. A layer of sodium fluoride is placed in a plastic tank and water is allowed to trickle through the layer, forming a solution of constant concentration that is fed to the water system.

Saturator

A procedure used to determine the concentration of fluoride ions in water; a color change takes place, following the addition of a chemical reagent. This is the chemical reagent used in this test.

SPADNS (Method)

A single water sample collected at one time from a single point.

Grab Sample

A series of individual or grab samples taken at different times from the same sampling point and mixed together.

Composite Sample

A plan for a laboratory operation that specifies the measures used to produce data of known precision and bias.

Quality Assurance (QA)

A laboratory program of continually checking techniques and calibrating instruments to ensure consistency in analytical results.

Quality Control (QC)

An instrument that measures the net and colloidal charge of suspended particles in liquid. The measurement is similar in theory to zeta potential determination and provides a reading that can be used to optimize coagulant dosages and maintain proper electrokinetic charge in coagulation control.

Streaming Current Detector

A laboratory procedure for evaluating coagulation, flocculation, and sedimentation processes. This is used to estimate proper coagulant dosage.

Jar Test

The most common chemical used for coagulation. Also called Aluminum Sulfate.

Alum

The gradual deterioration or destruction of a substance or material by chemical action. The action proceeds inward from the surface.

Corrosion

Mineral deposits left in pipelines and plumbing fixtures.

Scaling

The water treatment process intended to reduce the corrosive or scale-forming tendencies of water.

Stabilization

A knob or rust formed on the interior of cast-iron pipes as a result of corrosion.

Tubercle

Oxidized iron.

Rust

Another name for calcium hydroxide CaO, which is used in water softening and stabilization. Also called Unslaked Lime.

Quicklime

A conical tank filled with fine grain sand (seeding material). Supply water and chemicals (caustic soda, lime wash, or sodium carbonate) are injected through the bottom and mixed intensively, resulting in chemical precipitation that removes hardness from water, forming small hard pellets of calcium carbonate (CaCO3).

Pellet Reactor

The lime slurry formed when water is mixed with calcium hydroxide (hydrated lime or slaked lime).

Milk of Lime

Another name for calcium hydroxide (Ca(OH)2, which is used in water softening and stabilization. Also called Slaked Lime.

Hydrated Lime

The reintroduction of carbon dioxide into the water, either during or after lime-soda ash softening, to lower the pH of the water.

Recarbonization

A process of reversing the ion exchange softening reaction of ion exchange materials. Hardness ions are removed and replaced with nontroublesome ions, thus rendering the materials fit for reuse in the softening process.

Regeneration

A process used to remove hardness from water that depends on special materials known as resins. The resins trade nonhardness-causing ions (usually sodium) for the hardness-causing ions, calcium and magnesium. This process removes practically all of the hardness from water.

Ion exchange

In water treatment, the synthetic, bead-like material used in the ion exchange process.

Resin

A positive ion.

Cation

Ion exchange involving ions that have positive charges, such as calcium and sodium.

Cation Exchange

A negative ion.

Anion

The compound aluminum oxide, which is used to remove fluoride and arsenic from water by adsorption.

Activated Alumina (AA)

Ion exchange involving ions that have negative charges, such as chloride.

Anion Exchange

The water treatment process used primarily to remove organic contaminants from water. This involves the adhesion to the contaminants to an adsorbent, such as activated carbon.

Adsorption

Any material, such as activated carbon, used to adsorb substances from water.

Adsorbent

Activated carbon in a fine powder form. It is added to water in a slurry form primarily for removing those organic compounds causing tastes and odors.

Powdered Activated Carbon (PAC)

Activated carbon in a granular form, which is used in a bed, much like a conventional filter, to adsorb organic substances from water.

Granular Activated Carbon (GAC)

The volume of the tank holding an activated carbon bed, divided by the flow rate of water. This is expressed in minutes and corresponds to the detention time in a GAC filter bed.

Empty Bed Contact Time (EBCT)

A vertical, steel cylinder pressure vessel used to hold an activated carbon bed.

Contactor

The process of bringing air and water into close contact to remove or modify constituents in the water.

Aeration

The ratio of the volume of product water, or permeate produced, to raw water treated.

Recovery

A cylindrical tank containing packing material, with water distributed over the top and airflow introduced from the bottom by a blower. Commonly referred to as an Air Stripper.

Packed Tower

A pressure-driven process in which almost-pure water is passed through a semipermeable membrane and most ions (salts) are left behind. This process is primarily used for the desalination of seawater.

Reverse Osmosis (RO)

Raw water that has undergone pretreatment (acidification or scale inhibitor addition) prior to entering the filter membrane arrays.

Feedwater

The disposal of sludge by transporting it to a lagoon.

Lagooning

A process to remove a portion of the water from sludge.

Dewatering

To draw off the liquid from a basin or tank without stirring up the sediment in the bottom.

Decant

A pump consisting of an impeller on a rotating shaft enclosed by a casing that has suction and discharge connections. The spinning impeller throws water outward at high velocity, and the casing converts this high velocity to a high pressure.

Centrifugal Pump

A product description listing a chemical's identity, composition, and type or types; the hazard(s) associated with its use (is it flammable, an oxidizer, poisonous?); how it enters the body; the effects of exposure; health effects (short term, long term); the permissible exposure limit; how to handle spills or releases; and other related information.

Material Safety Data Sheet (MSDS) or Safety Data Sheet (SDS)

A type of respirator that supplies safe, Grade D (or better) breathing air to the wearer.

Self Contained Breathing Apparatus (SCBA)

A water treatment process in which relatively pure water passes through a porous membrane while particles, molecules, or ions of unwanted matter are excluded.

Membrane Filtration

A compound that is controlled through treatment to prevent the formation of calcium carbonate (hardness).

Calcium Bicarbonate

Disinfection using ultraviolet light.

Ultraviolet (UV) Disinfection

A characteristic of water, caused primarily by the salts of calcium and magnesium. Causes deposition of scale in boilers, damages in some industrial processes, may decrease the effectiveness of soap, and sometimes objectionable taste.

Hardness

Hardness caused primarily by bicarbonate.

Carbonate Hardness

Hardness caused by the salts of calcium and magnesium.

Noncarbonate Hardness

The principal hardness- and scale-causing compound in water.

Calcium Carbonate

The reintroduction of carbon dioxide into the water, either during or after lime-soda ash softening.

Recarbonization

A process used to remove hardness from water that depends on special materials known as resins. The resins trade nonhardness-causing ions (usually sodium) for the hardness-causing ions, calcium and magnesium. This process removes practically all the hardness from water.

Ion Exchange Process

The process of reversing the ion exchange softening reaction of ion exchange materials. Hardness ions are removed from the used materials and replaced with nontroublesome ions, thus restoring the exchange capacity of the resin for further softening.

Regeneration

A measure of a water's tendency to deposit scale or corrode pipes, based on pH, conductivity, hardness, alkalinity, and water temperature. An ideal range is near 0 (between -1 and 1) is considered balanced, meaning the water is neither scale-forming or corrosive: A negative number indicates undersaturation, meaning the water is corrosive and can dissolve metal pipes; A positive number indicates oversaturation, or the water is likely to deposit scale on pipes, filters, and other surfaces.

Langelier Saturation Index (LSI)

The maximum amount of a substance (like oxygen or calcium carbonate) that can dissolve in water under specific conditions (temperature, pressure, etc.). The addition of additional substance usually results in precipitation of that substance.

Saturation

A chemical process used to control scale in which a chelating agent "captures" scale-causing ions and holds them in solution, thus preventing them from precipitating out and forming scale. These agents can only bind with a single metal ion at once, while sequestering agents can bind to multiple metal ions simultaneously.

Chelation

A chemical process used to control scale formation, in which a sequestering agent holds scale-causing ions in solution, preventing them from precipitating out and forming scale. These agents can bind to multiple metal ions simultaneously, while chelating agents can only bind with a single metal ion at once.

Sequestration

(1) A measure of the energy possessed by water at a given location in the water system, expressed in feet. (2) A measure of pressure or force exerted by water, expressed in feet.

Head

Pressures measured by a gauge and expressed in terms of pounds per square inch.

Pounds per Square Inch Gauge (psig)

A measurement of the amount of energy in water due to water pressure.

Pressure Head

A line (hydraulic profile) indicating the piezometric level of water at all points along a conduit, open channel, or stream. In an open channel, this is the free water surface.

Hydraulic Grade Line (HGL)

The energy possessed per unit of weight of a fluid because of its elevation above some reference point (called the reference datum). This is also called Position Head or Potential Head.

Elevation Head

A measurement of the amount of energy in water due to its velocity, or motion.

Velocity Head

A line joining the elevations of the energy heads; a line drawn above the hydraulic grade line (HGL) by a distance equivalent to the velocity head of the flowing water at each section along a stream, channel, or conduit.

Energy Grade Line (EGL)

The energy or pressure reduction experienced by a fluid (like water or gas) as it flows through a pipe or channel due to friction between the fluid and the pipe walls.

Friction Head Loss

A flow rate of water measured at one particular instant, such as by a metering device, involving the cross-sectional area of a channel or pipe and the velocity of the water at that instant.

Instantaneous Flow Rate

An imaginary line through the center of a pump.

Pump Center Line

The difference in elevation between the pump center line and the free water surface of the reservoir feeding the pump. The piezometric surface of the water must be higher than the suction side of the pump for this to be measured.

Static Suction Head

The difference in elevation between the pump center line and the free water surface being pumped. The piezometric surface of the water must be lower than the suction side of the pump for this to be measured.

Static Suction Lift

The difference in height between the pump center line and the level of the discharge free water surface when the pump is not operating and there is no flow.

Static Discharge Head

The total height that a pump must lift water when moving it from one point to another. The vertical distance from the suction free water surface to the discharge free water surface. Essentially, the height the pump needs to lift the fluid.

Total Static Head

The energy losses in a piping system due to factors other than friction within the pipe itself, such as the resistance to flow as water passes through valves, fittings, inlets, and outlets of a piping system.

Minor Head Loss

The distance from the pump centerline at the suction of the pump to the point on the hydraulic grade line directly above it. This represents the total energy available at the pump's suction inlet.

Dynamic Suction Head

The distance from the pump centerline at the suction of the pump to the point on the hydraulic grade line directly below it. The total energy required to draw liquid from a source below the pump's centerline.

Dynamic Suction Lift

The difference in height between the hydraulic grade line (HGL) on the discharge side of the pump and the HGL on the suction side of the pump. This is a measure of the total energy that a pump must impart to the water to move it from one point to another.

Total Dynamic Head

A standard unit of power equal to 746 W (watts), or approximately 33,000 ft-lb/min.

Horsepower

The ratio of the total energy output to the total energy input, expressed as a percent.

Efficiency

The energy transferred by a force acting on an object as it moves a certain distance. This is achieved when a force causes an object to move a certain distance; it represents the transformation of energy from one form to another.

Work

The measure of the amount of work done in a given period of time, or the rate of doing work, measured in watts or horsepower.

Power

The portion of the power delivered to a pump that is actually used to lift water.

Water Horsepower

The power supplied to a pump by a motor.

Brake Horsepower

The horsepower equivalent to the watts of electric power supplied to a motor.

Motor Horsepower

The ratio of the total power input (electric current expressed as motor horsepower) to a motor and a pump assembly. to the total power output (water horsepower); expressed as a percent.

Wire-to-Water Efficiency

A curve or curves, showing the intersection of speed, dynamic head, capacity, brake horsepower, and efficiency of a pump.

Pump Characteristics Curves

The mark on the pump characteristics curve (H - Q or Head - Capacity curve) that indicates the head and capacity at which the pump is intended to operate for best efficiency in a particular installation.

Design Point

The combined effect of calcium and magnesium.

Total Hardness

The combined effect of hydroxyl alkalinity (OH-), carbonate alkalinity [CO3(-2)], and bicarbonate alkalinity (HCO3-).

Total Alkalinity

A US government agency responsible for implementing federal laws designed to protect the environment.

US Environmental Agency (USEPA)

Nonenforceable health-based goals published along with the promulgation of an MCL; originally called Recommended Maximum Contaminant Levels (RCMLs).

Maximum Contaminant Level Goal (MCLG)

The maximum permissible level of a contaminant in water as specified in the regulations of the Safe Drinking Water Act (SDWA).

Maximum Contaminant Level (MCL)

A new chemical compound formed by the reaction of disinfectants with organic compounds in water. At high concentrations, many of these are considered to be a danger to human health.

Disinfection By-Products (DBPs)

The average of four quarterly samples at each monitoring location to ensure compliance with the Stage 1 Disinfection By-Products Rule (DBPR).

Running Annual Average (RAA)

The product of the residual disinfectant concentration C, in milligrams per liter, and the corresponding disinfectant time T, in minutes. Minimum values are specified by the Surface Water Treatment Rule (SWTR) as a means of ensuring adequate kill or inactivation of pathogenic microorganisms in water.

C x T Value

A single water sample collected at one time from a single point.

Grab Sample

The oxygen dissolved in water, wastewater, or other liquid, usually expressed in milligrams per liter, parts per million, or percent saturation.

Dissolved Oxygen

A series of individual or grab samples collected at different times from the same sampling point and mixed together.

Composite Sample

A written record of a sample's history of SDWA compliance, from the time of collection to the time of analysis and subsequent disposal.

Chain of Custody

A laboratory method used for coliform testing that uses a nutrient broth placed in culture tubes. Gas production indicates the presence of coliform bacteria.

Multiple-Tube Fermentation (MTF) Method

A group of bacteria predominantly inhabiting the intestines of humans or animals, but also occasionally found elsewhere. Presence of this bacteria in water is used as an indication of fecal contamination (contamination by human or animal wastes).

Coliform Bacteria

The first major step in the multiple-tube fermentation process. The test presumes (indicates) the presence of coliform bacteria by inoculating multiple tubes of lauryl tryptose broth (LTB) with varying dilutions of sample; gas production after incubation indicates a positive test. Also known as the Most Probable Number (MPN) test.

Presumptive Test

In reference to the multiple-tube fermentation or membrane filter test, any sample that contained coliform bacteria.

Positive Sample or Presence

When referring to the multiple-tube fermentation or membrane filter test, any sample that does not contain coliform bacteria.

Negative Sample or Absence

The second major step in the multiple-tube fermentation method. This test confirms that positive results from the presumptive test are due to coliform bacteria by using the positive sample to inoculate a tube of brilliant green lactose bile broth (BGLB); gas formation within 48 hours indicates a positive test.

Confirmed Test

The third major step of the multiple-tube fermentation method. This test confirms that positive results from the confirmed test are due to coliform bacteria, by using the positive sample to inoculate a tube of lactose broth to verify acid and gas production. Also known as the "Quality Control" test.

Completed Test

This test is an approved bacteriological procedure for detection of both, total coliforms and E. coli within 24 hours without the need of confirmatory testing. This test is commercially known as the Colilert Test with a negative result being colorless; a total coliform positive result being a yellow color; and an E. coli positive result being a yellow/fluorescent color.

MMO - MUG Method (The Colilert Test)

A laboratory method used for coliform testing that uses an ultrathin filter with a uniform pore size smaller than bacteria (less than 1 micron). After a sample is forced through the filter, the trapped bacteria are cultured and incubated on a selective media (m-ENDO agar for coliform bacteria and m-TEC for E. coli), and identified and the coliform colonies are counted. Coliform bacteria exhibit red colonies with a metallic sheen and E. coli colonies exhibit a yellow, yellow-green or yellow-brown colonies.

Membrane Filter (MF) Method

This is a standard techniques used to asses the general microbial quality of water by counting the number of viable, culturable heterotrophic bacteria present in a sample. A significant increase in heterotrophic bacteria Colony-Forming Units (CFU) per milliliter can indicate potential water quality problems.

Heterotrophic Plate Count (HPC)

The acid neutralizing power of water.

Alkalinity

The base neutralizing power of water.

Acidity

A physical characteristic of water, which is most commonly tan or brown due to oxidized iron, but contaminants may lead to green or blue. Although this constituent in water is not regulated for health reasons, it is addressed through National Secondary Drinking Water Regulations (NSDWRs), which are non-enforceable guidelines focused on aesthetic concerns (including taste and odor).

Color

The color of water from which turbidity has been removed.

True Color

A characteristic of water that includes true color and the color caused by suspended matter.

Apparent Color

A procedure used to determine the amount of color in water that was developed in 1892 by chemist Allen Hazen. The scale ranges from 0 (clear) to 500 (deep yellow) Color Units (CU), where 1 color unit (CU) equals 1 mg/L of platinum in chloroplatinate ion form. The USEPA recommends through Secondary Maximum Contaminant Levels (SMCLs = non-enforceable regulations), that drinking water should not exceed 15 color units. This also known as the Alpha-Hazen Scale or APHA Color.

Platinum-Cobalt Method

This is a measure of odor intensity, which is depicted by a number indicating the greatest dilution of a water sample (using odor-free water) that still yields a noticeable odor. Although odor in water is not regulated for health reasons, it is addressed through National Secondary Drinking Water Regulations (NSDWRs), which are non-enforceable guidelines focused on aesthetic concerns (including taste and color).

Threshold Odor Number (TON)

A physical characteristic of water that makes water appear cloudy. The condition is caused by the presence of suspended matter.

Turbidity

An instrument that determines turbidity by measuring the amount of light scattered by turbidity in a water sample. It is the ONLY instrument approved by the USEPA to measure turbidity in treated drinking water.

Nephelometer

A method that uses a graph or other diagram to solve formulas and equations.

Nomographic Method

Any laboratory procedure that uses titration to determine the concentration of a constituent in water.

Titrimetric Method

The chlorine residual produced by the reaction of chlorine with substances in the water; most often it is formed by the reaction of chlorine and ammonia. This is not as effective as a disinfectant as is free chlorine residual. This is also known as Chloramines.

Combined Chlorine Residual

The point at which the chlorine dosage has satisfied the chlorine demand.

Breakpoint

The addition of chlorine until the chlorine demand has been satisfied and free chlorine residual is available for disinfection.

Breakpoint Chlorination

The quantity of chlorine consumed by reaction with other substances in water.

Chlorine Demand

An analytical procedure that uses an electrode connected to a millivoltmeter to measure the concentration of a constituent in water.

Electrode Method

This is a standard test for measuring dissolved oxygen (DO) in water. A modification of the standard Winkler (iodometric) method that uses an alkali-iodide-azide reagent to make the procedure less subject to interferences.

Modified Winkler Method

A colorimetric procedure used to determine the concentration of fluoride ion in water. (sodium 2-[parasulfophenylazo]-1.8 dihydroxy-3,6-napthalene disulfonate) is the chemical reagent used in the test.

SPADNS Method

A spectrophotometer used to determine the concentration of metals in water and other types of samples.

Atomic Adsorption Spectrophotometer (AA)

A measure of a water's acidity or alkalinity. A scale of 1 to 14 is used, with 0 being extremely acidic and 14 being extremely alkaline.

The result of a general analysis performed on a water sample to determine the total organic content of the water.

Total Organic Carbon (TOC)

A techniques used to measure the concentration of organic compounds in water.

Gas Chromatography (GS)

A laboratory procedure for evaluating coagulation, flocculation, and sedimentation processes. This is used to estimate the proper coagulant dosage.

Jar Test

The water treatment process intended to reduce the corrosive or scale-forming tendencies of water.

Stabilization

The gradual deterioration or destruction of a substance or material by chemical action. The action proceeds inward from the surface.

Corrosion

Mineral deposits left in pipelines and plumbing fixtures.

Scaling

A knob of rust formed on the interior of cast-iron pipes as a result of corrosion.

Tubercles

Bacteria that use dissolved iron as an energy source. They can create serious problems in a water system because they form large, slimy masses that clog well screens, pumps, and other equipment.

Iron Bacteria

Oxidized iron or iron oxide.

Rust

Tendency to deteriorate metal, such as pipe, through electrochemical processes.

Corrosive or Aggressive Water

A form of localized corrosion that can form deep pits and tubercles.

Concentration Cell Corrosion

A listing of metals and alloys according to their corrosion potential.

Galvanic Series

A form of localized corrosion caused by the connection of dissimilar metals in an electrolyte, such as water.

Galvanic Corrosion

The point at which a solution can no longer dissolve any more of a particular chemical. Precipitation of the chemical will occur beyond this point.

Saturation Point

Another name for calcium oxide (CaO), which is used in water softening and stabilization.

Quicklime or Unslaked Lime

A thin mixture of water and any insoluble material, such as activated carbon.

Slurry

The lime slurry formed when water is added with calcium hydroxide (also known as: slaked lime, hydrated lime, or caustic lime).

Milk of Lime

A method of determining the rate of corrosion or scale formation by placing metal strips (coupons) of a known weight in the pipe and examining them for corrosion after a period of time.

Coupon Test

A process used to remove carbonate hardness from water.

Lime-Soda Ash Process

The part of a quicklime feeder that mixes the quicklime with water to form hydrated lime (calcium hydroxide, hydrated lime, or caustic lime).

Slaker

The addition of water to quicklime (calcium oxide CaO) to form calcium hydroxide, which then can be used in the softening or stabilization processes.

Slake

The process of quickly mixing a chemical solution uniformly through the water.

Rapid or Flash Mixing

The water treatment process following coagulation, that uses gentle stirring to bring suspended particles together so they will form larger, more settleable clumps called floc.

Flocculation

The water treatment process that involves reducing the velocity of water in basins so that the suspended material can settle out by gravity.

Sedimentation

A basin or tank in which water is retained to allow settleable matter, such as floc, to settle by gravity.

Sedimentation Basin

An upflow basin in which coagulation, flocculation, and sedimentation processes are all combined. This is primarily used in the lime softening of water.

Solids-Contact Basin

A process to remove a portion f water from sludge.

Dewatering

The portion of total hardness caused by magnesium compounds, such as magnesium carbonate and magnesium sulfate.

Magnesium Hardness

The water treatment process(s) that converts small particles of suspended solids into larger, more settleable clumps.

Coagulation-Flocculation

A compound formed when natural organic substances from decaying vegetation and soil (such as humic and fulvic acids) react with chlorine.

Trihalomethanes (THMs)

A treatment unit that removes calcium and magnesium from water using ion exchange resins.

Ion Exchange Water Softener

The predetermined amount of source water that is routed past water softeners and then blended with softened water to achieve the desired level of finished water hardness.

Percent Bypass

A membrane-based water treatment process that uses an electric field to selectively remove ions from water, which is commonly used for desalination rather than exclusively for softening.

Electrodialysis

Activated carbon in fine powdered form. It is added to water in a slurry form primarily for removing those organic compounds causing tastes and odors.

Powdered Activated Carbon (PAC)

Activated carbon in granular form, which is used in a bed, much like a conventional filter, to adsorb organic substances from water.

Granular Activated Carbon (GAC)

The time it takes for a bed of adsorbent to lose its adsorptive capacity. When this occurs, the bed must be replaced with fresh adsorbent.

Bed Life

An accumulation of media grains and suspended material that creates clogging problems in filters.

Mudballs

A condition in the filtering treatment cycle where contaminants, such as organics or turbidity, begin to pass through the treatment process.

Breakthrough

The process of bringing water and air into close contact to remove or modify constituents in the water.

Aeration

Air Binding

A pressure-driven process in which almost-pure water is passed through a semipermeable membrane and most salts (ions) are left behind. This process is primarily used for desalination of seawater.

Reverse Osmosis (RO)

Raw water that has undergone pretreatment (acidification or scale inhibitor addition) prior to entering the membrane arrays.

Feedwater

The amount of energy used (lost) by water in moving from one point to another.

Head Loss

The water that does not pass through the membrane, carries away the rejected matter, and must be disposed of.

Reject Water

A device that produces ozone by passing an electrical current through air or oxygen.

Ozone Generator

A tank used to transfer ozone to water. A common type applies ozone under pressure through a porous stone at the bottom of the tank.

Ozone Contactor

The accumulated solids separated from water during treatment.

Sludge

The most common Chemical used for coagulation. It is also called aluminum sulfate.

Alum

A three-stage process that describes how nutrients and biological activity influence water quality. The Oligotrophic Stage is associated with low nutrients and limited algae production and biological activity. The Mesotrophic Stage involves a moderate amount of these constituents. The Eutrophic Stage is rich in nutrients and biological activity.

Trophic Cycle

The layering of water as a result of temperature differences.

Thermal Stratification

Extraction of water through the bank of a river or through the bottom using wells or buried collection piping.

River Bank Filtration

an area from which surface runoff is carried away by a single drainage system.

Watershed

Any introduction into water of microorganisms, chemicals, wastes, or wastewater in a concentration that makes the water unfit for its intended use.

Contamination

The reduction of water usage, accomplished primarily by preventing waste.

Water Conservation

The implementation of techniques by a utility to save water by managing the available supply.

Supply Management

Water use that does not pass through meters and thus, is not paid for (including water that is wasted).

Unaccounted-For Water

The selection and use of trees, shrubs, and plants that require small amounts of water for landscaping.

Xeriscaping

A water right that allows the owners of land abutting a stream or other natural body of water, to use that water.

Riparian Doctrine

A water rights doctrine in which the first user has the right to the water before subsequent users.

Prior Appropriation Doctrine

A water rights term in which water use is prioritized based on who has been using the water for the longest time.

Priority in Time

A water rights term indicating that the water is being used for good purposes.

Beneficial Use

A water rights term referring to water that is completely owned by one person.

Absolute Ownership

A water rights term indicating that the water use is acceptable in general terms.

Reasonable Use

The land use that occurs on top of an aquifer.

Overlying Use

A rule that contends the Overlying Use rule is not Absolute right, but is related to the rights of other overlying users. The rule is used when there is not enough water to satisfy all overlying uses.

Correlative Rights

A water use system in which permits to use the water are regulated so that overdraft cannot occur.

Appropriation-Permit System

The maximum permissible level of a contaminant in water as specified in the regulations of the Safe Drinking Water Act (SDWA).

Maximum Contaminant Level (MCL)

Nonenforceable health-based goals published along with the promulgation of an MCL. Originally called Recommended Maximum Contaminant Levels (RCMLs).

Maximum Contaminant Level Goal (MCLG)

A composite sample in which individual sample volumes are proportional to the flow rate at the time of sampling.

Flow-Proportional Composite Sample

A composite sample consisting of several equal-volume samples taken at specific times.

Time Composite Sample

= Water Used (in gal per day) / Total Number of People

Gallons per Capita Day (gpcd)

It is the sum of all the daily flows, divided by the total number of daily flows used.

Average Daily Flow (ADF)

A water right that allows the owners of land abutting a stream or other natural body of water to use that water.

Riparian Doctrine

A water rights doctrine in which the first user has the right to the water before subsequent users.

Prior Appropriation Doctrine

The assigning of water rights based on who has been sing the water the longest.

Priority in Time

A water rights term indicating that the water is being used for good purposes.

Beneficial Use

A water rights term referring to water that is completely owned by one person.

Absolute Ownership

A water rights term indicating that the water is acceptable, in general.

Reasonable Use

The land that occurs on top of an aquifer.

Overlying Use

A rule that contends that the overlying use rule is not absolute ownership, but it is related to the rights of other overlying users. This rule is used when there is not enough water to satisfy all overlying uses.

Correlative Rights

A water use system in which permits to use the water are regulated so overdraft can not occur.

Appropriation-Permit System

A water system using water from a lake or stream for its supply.

Surface Water System

A water system using wells, springs, or infiltration galleries as its source of supply.

Groundwater System

A water system that purchases water from another water system, so it only provides distribution and minimal treatment.

Purchased Water System

A distribution system layout involving a complete loop of arterial mains (sometimes called trunk mains or feeders) around the area being served, with the branch mains projecting inward. Such a system minimizes dead ends.

Arterial-Loop System

A distribution system layout in which all of the mains are connected to eliminate dead ends.

Grid System

A distribution system layout that centers around a single arterial main, which decreases in size with length. Branches are taken off at right angles, with subbranches from each branch.

Tree System

A formula for the velocity of flow in a pipe.

Hazen-Williams Formula

The study of fluids in motion or under pressure.

Hydraulics

Pressure that exists in water although the water does not flow.

Static Pressure

The force on a unit of area.

Pressure

Pressure that exists in water as moving energy.

Dynamic Pressure

A measure of pressure.

Pounds per Square Inch (psi)

The pressure exerted by water at rest (for example, in a nonflowing pipeline).

Hydrostatic Pressure

(1) A measure of the energy possessed by water at a given location in the water system, expressed in feet. (2) A measure of the pressure or force exerted by water, expressed in feet.

Head

The speed at which water moves; measured in ft/sec or m/sec.

Velocity

The water pressure as measured by a gauge and is expressed as "psig." This is not total pressure; total pressure (absolute pressure) also includes atmospheric pressure (about 14.7 psi at sea level) when exerted on the water. However, since atmospheric pressure is exerted everywhere (against the outside of a pipe as well as the inside of a pipe, for example), it is generally not written into water system calculations.

Gauge Pressure

The total pressure in the system, including both the pressure of the water and the pressure of the atmosphere (about 14.7 psi at sea level).

Absolute Pressure or Total Pressure

A measure of the energy in water due to water pressure.

Pressure Head

A line (hydraulic profile) indicating the piezometric level of water at all points along a conduit, open channel, or stream. In an open channel, this is the free water surface.

Hydraulic Grade Line (HGL)

The energy possessed per unit of weight of a fluid because of its elevation above some reference point (called the "reference datum"). This is also called position head or potential head.

Elevation Head

A measurement of the amount of energy in water due to its velocity, or motion.

Velocity Head

A line joining the elevation of energy heads; a line drawn above the hydraulic grade line by a distance equivalent to the velocity head of the flowing water at each section along a stream, channel, or conduit.

Energy Grade Line (EGL)

The hydrostatic pressure within a pipe.

Internal Pressure

Any load placed on the outside of a pipe from backfill, traffic, or other sources.

External Load

The potentially damaging slam, bang, or shudder that occurs in a pipe when a sudden change in water velocity (usually as a result of someone too rapidly starting a pump or operating a valve) creating a great increase in water pressure.

Water Hammer

A measure of the ability of pipe or other material to resist breakage when it is pulled lengthwise.

Tensile Strength

The ability of a material to bend (flex) without breaking.

Flexural Strength

The pipeline or aqueduct used for water transmission, i.e., movement of water from the source to the treatment plant and from the plant to the distribution system.

Transmission Line

The growth of nodules (tubercles) on the pipe interior, which reduces the inside diameter and increases the pipe roughness.

Tuberculation

The network of pipes in a particular facility, such as a water treatment plant, that carry water or wastes for that facility.

In-Plant Piping System

Any pipe in the distribution system other than the service line.

Distribution Main

The pipe (and all appurtenances) that runs between the utility's water main and the customer's place of use, including fire lines.

Service Line

A pipe joint that consists of two machined surfaces that are tightly bolted together with a gasket between them.

Flanged Joint

A pipe joint for ductile-iron that uses bolts, flanges, and a special gasket.

Mechanical Joint

A pipe joint consisting of a bell with a specially designed recess to accept a rubber ring gasket. The spigot end must have a beveled edge so it will slip into the gasket without catching or tearing it.

Push-On Joint

Reinforced concrete placed in compression by highly stressed, closely spaced, helically wound wire. The prestressing permits the concrete to withstand tension forces.

Prestressed Concrete

A method of preventing cave-ins that involves excavating the sides of a trench at an angle (the angle of repose) so that the sides will be stable.

Sloping

The process by which organic compounds pass through a plastic pipe.

Permeation

A framework of wood and/or metal constructed against the walls of a trench to prevent cave-in of the earth walls.

Shoring

A method to protect workers against cave-ins through the use of a steel box (trench box), that is open at the top, bottom, and ends. This allows workers to work inside the box while installing water mains.

Shielding

A method to protect workers against cave-ins by installing tightly spaced upright planks against each other to form a solid barrier against the faces of the excavation.

Sheeting

In tapping, the section of the main that is cut out by the drilling machine.

Coupon

(1) A force resulting from water under pressure and motion. (2) In general, any pushing force. This force pushes against fittings, valves, and hydrants; it can cause couplings to leak or pull apart entirely.

Thrust

A mass of concrete cast in place between a fitting to be anchored against thrust and the undisturbed soil at the side or bottom of the pipe trench.

Thrust Block

A block of concrete, often a roughly shaped cube, cast in place below a fitting to be anchored against vertical thrust, and tied to the fitting with anchor rods.

Thrust Anchor

A device for restraining joints that are particularly useful in locations where other existing utilities or structures are so numerous that thrust blocks are precluded.

Restraining Fitting

A method of disinfecting new or repaired water mains in which chlorine is continuously added to the water being used to fill the pipe, so that a constant concentration can be maintained.

Continuous Feed Method

(1) The operation of refilling an excavation, such as a trench, after a pipeline or other structure has been placed into the excavation. (2) The material used to fill the excavation.

Backfill

A method of disinfecting new or repaired water mains in which a high dosage of chlorine is added to a portion of the water used to fill the pipe. This slug of water is allowed to pass through the entire length of pipe being disinfected.

Slug Method

A method of disinfecting new or repaired water mains in which calcium hypochlorite tablets are placed in a section of pipe. As the water fills the pipe, the tablets dissolve, producing a chlorine concentration.

Tablet Method

A pit-like enclosure that protects water meters installed outside of buildings and allows access for reading the meter.

Meter Box

A form of localized corrosion caused by the connection of two dissimilar metals in an electrolyte, such as water.

Galvanic Corrosion

A valve used to join a service line to a street water main. This valve cannot be operated from the surface.

Corporation Stop

A shutoff valve attached to a water service line from a water main to a customer's premises, usually placed near the customer's property line. It may be operated by a valve key to start or stop flow to the customer's water supply line.

Curb Stop

A cylinder placed around the curb stop and extending to the ground surface to allow access to the valve.

Curb Box

A connection made to a water main that is full or under pressure.

Wet Tap

A connection made to a water main that is empty.

Dry Tap

The process of connecting laterals and service lines to water mains and/or other laterals.

Tapping

A device attached around a water main to hold the corporation stop. These are used with water mains that have thinner walls to prevent leakage.

Service Saddle

A mechanical device installed in a pipeline to control the amount and direction of water flow.

Valve

A valve installed in a pipeline to shut off flow in a portion of the pipe, for the purposes of inspection or repair. Such valves are usually installed in the mainlines.

Isolation Valve

A valve with a horizontal disc for automatically regulating water pressures in a main to a preset value.

Pressure-Reducing Valve

A valve that automatically shuts off water flow when the water flow in an elevated tang reaches a preset elevation, then opens again when the pressure on the system side is less than that on the tank side.

Altitude Valve

A valve that opens automatically when the water pressure reaches a preset limit to relieve stress on a pipeline.

Pressure-Relief Valve

An air valve placed at a high point in a pipeline to release air automatically, thereby preventing air binding and pressure buildup.

Air-Relief Valve

A valve in which the closing element consists of a disc that slides across an opening to stop the flow of water.

Gate Valve

A gate valve in which the valve stem does not move up and down as it is rotated.

Nonrising-Stem Valve

A gate valve that is designed such that the valve-operating mechanism does not have to lift the weight of the gate to open the valve.

Horizontal Valve

A small valve installed in parallel with a larger valve. This is used to equalize the pressure on both sides of the disc of the larger valve before the larger valve is opened.

Bypass Valve

A special shutoff valve used with a tapping sleeve.

Tapping Valve

A specially designed gate valve used with a sleeve that allows the valve to be placed in an existing main.

Cutting-In Valve

A shutoff valve that can be inserted by a special apparatus into a pipeline while the line is in service under pressure.

Insertion Valve

A gate valve with a disc that has a resilient material attached to it to allow leak-tight shutoff at high pressure,

Resilient-Seated Valve

A valve having a round ball-like shell and horizontal disc.

Globe Valve

A gate valve that uses a relatively thin gate or blade that slides up and down in a recess to stop low-pressure flows, where tight shutoff is not important.

Slide Valve

A valve that is similar to a globe valve, except that a tapered metal shaft fits into s metal seat when the valve is closed; available only in small sizes and are primarily used for precise throttling of flow.

Needle Valve

A dual-function air valve that: (1) permits entrance of air into a pipe being emptied, thus preventing a vacuum. (2) allows air to escape in a pipe being filled or under pressure.

Air-and-Vacuum Relief Valve

A valve that is closed by pinching shut an interior liner.

Pinch Valve

A valve which the moveable element is a cylindrical or conical plug.

Plug Valve

A valve consisting of a ball resting in a cylindrical seat. A hole is bored through the ball to allow water to flow when the valve is open; when the ball is rotated 90 degrees, the valve is closed.

Ball Valve

A valve in which a disc rotates on a shaft as the valves opens or closes. In the fully open position, the disc is parallel to the axis of the pipe.

Butterfly Valve

A valve designed to open in the direction of normal flow and close with the reversal of flow. An approved valve has substantial construction and suitable materials, is positive in closing permitting no leakage in a direction opposite to normal flow.

Check Valve

A device, usually pneumatically or electrically powered, that is used to operate valves.

Actuator

A metal, concrete, or composite box or vault set over a valve stem at ground surface to allow access to the stem so that the valve can be opened or closed. A cover for the box is usually provided at the surface to keep out dirt and debris.

Valve Box

The rate of flow, usually measured in gallons per minute (gpm) or (L/min), that can be delivered from a water distribution system at a specified residual pressure for fire fighting. When delivery is to fire department pumpers, the specified residual pressure is generally 20 psi (140 kPa).

Fire Flow

A hydrant for which the main valve is located in the base. The barrel is only pressurized with water then the main valve is opened and when the main valve is closed, the barrel drains. This type of hydrant is especially appropriate for use in areas where freezing weather occurs.

Dry-Barrel Hydrant

A dry-barrel hydrant in which the threaded end of the main rod and the revolving or operating nut are not sealed from the water in the barrel when the main valve of the hydrant is open, and the hydrant is in use.

Wet-Top Hydrant

A dry-barrel hydrant in which the threaded end of the main rod and the revolving or operating nut is sealed from the water when the main valve is open, and the hydrant is in use.

Dry-Top Hydrant

A two-part, dry-barrel post hydrant with a coupling or other device joining the upper and lower sections. The coupling and barrel are designed to break cleanly when the hydrant is struck by a vehicle, preventing water loss and allowing easy repair.

Breakaway Hydrant

A fire hydrant with no main valve. Under normal, nonemergency conditions, the barrel is full and pressurized (as long as the lateral piping to the hydrant is under pressure and the gate valve ahead of the hydrant is open). Each outlet has an independent valve that controls the discharge from that outlet. This type of hydrant is mainly used in areas where the temperatures do not drop below freezing because this hydrant has no drain mechanism.

Wet-Barrel Hydrant

A fire hydrant with a two-piece barrel that has the main valve located at ground level.

Warm-Climate Hydrant

A fire hydrant with the entire barrel and head below ground elevation. The head, with operating nut and outlet nozzles, are encased in a box with a cover that is flush with the ground line. This is usually a dry-barrel hydrant.

Flush Hydrant

The upper part of the main hydrant assembly, including the outlet nozzles and outlet-nozzle caps. This component is usually constructed out of gray cast iron. Also known as the nozzle section or head.

Upper Section

A nut, usually pentagonal or square, that is rotated with a wrench to open or close a valve or hydrant valve. This may be a single component or it may be combined with a weather shield.

Operating Nut

The top cover or closure on the hydrant upper section. It is removeable for the purposes of repairing or replacing the internal parts of the hydrant.

Bonnet

A threaded bronze outlet on the upper section of a fire hydrant, providing a point of hookup for hose lines or suction hose from the hydrant to a pumper truck.

Outlet Nozzle

The part of a dry-barrel hydrant that includes the lower barrel, the main valve assembly, and the base.

Lower Section

The section of the a hydrant that carries the water flow between the base and upper section. This component is usually buried in the ground with the connection to the upper section protruding approximately 2 in. (50 mm) above the ground line.

Lower Barrel

In a dry-barrel hydrant, this is the valve in the hydrant's base that is used to pressurize the hydrant barrel, allowing water to flow from any open outlet nozzle.

Main Valve

The inlet structure of a fire hydrant. An elbow shaped piece that is usually constructed as a grey cast-iron casting. Also known as the shoe, inlet, elbow, or foot piece.

Base

The practice of dropping a weighted string down the barrel of a hydrant to check if the barrel is fully drained.

Stringing (Hydrants)

A nut, used in dry-barrel hydrants, that is screwed on the threaded section of the main rod. It bottoms at the base of the packing plate, or revolving nut, and terminates downward travel (opening) of the hydrant valve.

Travel-Stop Nut

In any distribution system, storage of water in a tank supported on a tower above the surface of the ground.

Elevated Storage

The required fire flow and the duration for which it is needed, usually expressed in gallons (or liters) per minute for a certain number of hours. Also used to denote the total quantity of water needed to deliver the required fire flow for a specific number of hours.

Fire Demand

A system using an airtight tank in which air is compressed over water (separated by a flexible diaphragm). The air imparts pressure to the water in the tank and the attached distribution pipelines.

Hydropneumatic System

The vertical supply pipe to an elevated tank.

Riser

An electrical system for preventing corrosion to metals, particularly metallic pipe and tanks.

Cathodic Protection

The study of the combined effects of electricity and magnetism.

Electromagnetics

A state in which electrons have accumulated but are not flowing from one position to another.

Static Electricity

Current that flows continuously in one direction.

Direct Current (DC)

Electrical current that reverses its direction in a periodic manner.

Alternating Current (AC)

Instruments required to operate the monitoring system by obtaining information relating to water flow, pressure, level, and temperature.

Primary Instrumentation

A level-sensing device that forces a constant volume of air into the liquid for which the level is being measured.

Bubbler Tube

A sensor, made of two dissimilar metals, that measures temperature.

Thermocouple

(1) A measure of electrical potential (electrical pressure), measured in volts. -One volt will send a current of 1 ampere through a resistance of 1 ohm. (2) In telemetry, a signal which the electromotive force (measured in volts) varies as the parameter being measured varies.

Voltage

A semiconductor type of sensor that measures temperature.

Thermistor

(1) The flow rate of electricity, measured in amperes. (2) In telemetry, a signal whose amperage varies as the parameter being measured varies.

Current

A characteristic on an electrical circuit that tends to restrict the flow of current, similar to friction in a pipeline. This characteristic is measured in ohms.

Resistance

A measure of the amount of work done per unit of time by an electrical circuit, expressed in watts.

Power

An instrument for measuring real power in watts, stated as kilowatt-hours (kW-h).

Wattmeter

An electrical measuring device, consisting of an indicator needle attached to a coil of wire, placed within a field of permanent magnetism. The needle moves when an electric current is passed through the coil.

D'Arsonval Meter

Instruments that display information provided by sensors.

Secondary Instrumentation

(1) The part of a meter that converts the signal from the sensor into a form that can be read by the operator; also called the receiver-indicator. (2) In a telemetry system, the device that converts the signal from the transmission channel into a form that the indicator can respond to.

Receiver

The part of the instrument that displays the information about a system being monitored. Generally, either an analog or digital display.

Indicator

The receiving device in a digital telemetry system.

Control Terminal Unit (CTU)

A computer terminal used to monitor the status of control elements, monitor and transmit inputs from instruments, and respond to data requests and commands from the master station.

Remote Terminal Unit (RTU)

A system of sending data over long distances, consisting of a transmitter, a transmission channel, and a reciever.

Telemetry

The use of a single wire or channel to carry the information for several instruments or controls.

Multiplexing

A method of sending several signals simultaneously over a single channel.

Tone-Frequency Multiplexing

A techniques of checking the value of each of several instruments, one after another.

Scanning

A technique of monitoring several instruments over a single communications channel with a receiver the periodically asks each instrument to send current status.

Polling

Capable of sending and receiving data at the same time.

Full Duplex

A means by which an operator sends control signals back to the site of a transmitting sensor using a single transmission line.

Duplexing

Capable of sending or receiving data, but not at the same time.

Half Duplex

Related to a telemetry or data transmission that can move data through a single channel inly in one direction.

Simplex

A type of system control in which personnel manually operate the switches and levers to control equipment from the physical location of the equipment.

Manual Control

A means of controlling equipment in a variety of ways.

Control System

A system in which personnel in a central location manually control equipment at a distant site.

Remote Manual Control

A mode of controlling equipment in which the equipment is turned fully on when a measured parameter reaches a preset value, then turned fully off when it returns to another preset value.

On - Off Differential Control

A system in which many equipment control actions happen automatically, but some situations require human intervention.

Semiautomatic Control

A mode of automatic control in which a valve or motor is activated slightly to respond to small variations in the system, but activated at a greater rate to respond to larger variations.

Proportional Control

A control system that measures a variable and adjusts the equipment proportionally.

Feed Forward Proportional Control

A form of computerized control that automatically adjusts for changing conditions to produce the correct output, so that operator intervention may be minimized.

Closed-Loop Control

A methodology of involving equipment that both, acquires data on an operation and provides limited to total control of equipment in response to data.

Supervisory Control and Data Acquisition (SCADA)

Alternating current (AC) power in which the current flow reaches a peak in each direction only once per cycle.

Single-Phase

The most common type of induction electric motor. The rotor consists of a series of aluminum or copper bars parallel to the shaft, resembling a squirrel cage.

Squirrel-Cage Induction Motor

Alternating current (AC) power in which the current flow reaches three peaks in each direction, during each cycle.

Three-Phase

The stationary member of an electric generator or motor.

Stator

An electric motor in which the rotor turns at the same speed as the rotating magnetic field produced by the stator. This type of motor has no slip.

Synchronous Motor

A type of electric motor, similar to a squirrel-cage induction motor, but easier to start and capable of variable-speed operation.

Wound-Rotor Induction Motor

A device that is part of the rotor of certain designs of motors and generators. The motor unit's brushes rub against the surface of the spinning communicator, allowing current to be transferred between the rotor and the external circuits.

Communicator

A motor-control device that uses a small push-button switch to activate a control relay, which sends electrical current to the motor.

Starter

`An electric controller that uses less than the line voltage to start the motor. Used when full line voltage may overload or damage the electrical system.

Reduced-Voltage Controller

The rotating set of vanes that forces water through a pump.

Impeller

The general class of pumps that uses a rapidly turning impeller to impart kinetic energy or velocity to fluids. The pump casing then converts this velocity head in part, to pressure head.

Velocity Pump

A pump consisting of an impeller on a rotating shaft, enclosed by a casing that has suction and discharge connections. The spinning impeller throws water outward at a high velocity, and throws water outward at a high velocity, and the casing shape converts this high velocity into high pressure.

Centrifugal Pump

(1) A centrifugal pump in which fixed guide vanes (diffusers) partially convert the velocity energy of water into pressure head as the water leaves the impeller. (2) A regenerative turbine pump.

Turbine Pump

A centrifugal pump, commonly of the multistage diffuser type, in which the pump shaft is mounted vertically.

Vertical Turbine Pump

Slip

A type of positive displacement pump consisting of a closed cylinder containing a piston or plunger to draw liquid through an inlet valve and force it out through an outlet valve. When the piston acts on the liquid in one end of the cylinder, the pump is termed to be single-action; when the piston acts in both ends, the pump is termed double-action.

Reciprocating Pump

A type of positive displacement pump consisting of elements resembling gears that rotate in a close-fitting pump case. The rotation of these elements draws in and discharges water being pumped. Such pumps act with neither nor discharge valves, operate at almost any speed, and do not depend on centrifugal forces to lift water.

Rotary Pump

A check valve placed in the bottom of the suction pipe of a pump, which opens to allow water to enter the suction pipe, but closes to prevent water from passing out of it at the bottom end.

Foot Valve

A condition that can occur when pumps are run too fast or water is forced to change direction too quickly. During this condition, a partial vacuum forms near the pipe wall or impeller blade, causing potentially rapid pitting of the metal.

Cavitation

A sensor for measuring the rotational speed of a shaft.

Tachometer Generator

A centrifugal pump in which the water only enters from one side of the impeller.

Single-Suction Pump

A centrifugal pump in which water enters from both sides of the impeller.

Double-Suction Pump

Rings made of brass or bronze placed on the impeller and/or casing of a centrifugal pump to control the amount of water that is allowed to leak from the discharge to the suction side of the pump.

Wear Rings

(1) The bearing-supported rod in a pump, turned by a motor, on which the impeller is mounted. (2) The portion of a butterfly valve that is attached to the disc and a valve actuator; this opens and closes the disc as the actuator is operated.

Shaft

Rings of graphite-impregnated cotton, flax, or synthetic materials, used to control leakage along a valve stem or a pump shaft.

Packing

A perforated ring placed around a pump shaft in the stuffing box. Water from the pump discharge is piped to this ring so that it will form a liquid seal around the shaft and lubricate the packing.

Lantern Ring

A seal placed on the pump shaft to prevent water from leaking from the pump along the shaft. This also prevents air from entering the pump. These are an alternate to backing rings.

Mechanical Seals

Antifriction device used to support and guide pump and motor shafts.

Bearing

A device that connects the pump shaft to the motor shaft.

Coupling

A device installed in a pipe under pressure for measuring and registering the quantity of water passing through.

Water Meter

A type of meter consisting of a measuring chamber of known size that measures the volume of water flowing through it by means of a piston or a disc.

Positive-Displacement Meter

A type of positive displacement meter that uses a hard rubber disc that wobbles (rotates) in proportion to the volume of water flowing through the meter.

Nutating-Disc Meter

A water meter consisting of two single meters of different capacities and a regulating valve that automatically diverts all or part of the flow rate and shift the flow to the meter that can most accurately measure it.

Compound Meter

A device for determining flow rate by measuring the velocity of moving water. Turbine meters, propeller meters, and multijet meters are common types. Compare with positive displacement meter.

Current Meter

A meter that measures daily flow but allows emergency flow to bypass the meter. This meter consists of a weight-loaded check valve in the main line that remains closed under normal usage and a bypass around the valve containing a positive displacement meter.

Detector-Check Meter

A meter that measures flow rates by measuring the speed at which a turbine spins in water, indicating the velocity at which the water is moving through a conduit of known cross-sectional area.

Turbine Meter

A type of current meter in which a vertically mounted turbine wheel is spun by jets of water from several ports around the wheel.

Multijet Meter

A meter that measures flow rate by measuring the speed at which a propeller spins as an indication of the velocity at which the water is moving through a conduit of a known cross-sectional area.

Propeller Meter

Any flowmeter that that diverts a small portion of the main flow and measures the flow rate of that portion as an indication of the rate of the main flow. The rate of the diverted flow is proportional to the rate of the main flow.

Proportional Meter

A pressure-differential meter used for measuring flow of water or other fluids through closed conduits or pipes consisting of a Venturi tube and a flow registering device. The difference in velocity head between the entrance and contracted throat of the tube is an indication of rate of flow.

Venturi Meter

A type of flowmeter consisting of a section of pipe blocked by a disc pierced with a small hole or orifice. The entire flow passes through the orifice, creating a pressure drop proportional to the flow rate.

Orifice Meter

A flow-measuring device in which the movement of water induces an electrical current proportional to the rate of flow.

Magnetic Meter

A meter that utilizes sound-generating and -receiving sensors (transducers) attached to the sides of the pipe.

Ultrasonic Meter

The water treatment process that kills disease-causing organisms in water, usually by the addition of chlorine.

Disinfection

C x T Value

the process of disinfecting water through the controlled use of chlorine; usually accomplished by adding gaseous chlorine, liquid sodium hypochlorite, or solid calcium hypochlorite.

Chlorination

The amount of chlorine that will combine with organic and inorganic materials to form chlorine compounds when added to water; once the demand has been satisfied, additional chlorine will not combine with the organic and inorganic materials.

Chlorine Demand

The total of all chlorine compounds with disinfecting properties, plus any remaining uncombined chlorine.

Chlorine Residual

The point at which the chlorine dosage has satisfied the chlorine demand.

Breakpoint

A container that holds 150 lb (69 kg) of chlorine and has a total filled weight of 250-285 lb (110-130 kg).

Chlorine Cylinder

A reusable, welded tank that holds 2,000 lb (910 kg) of chlorine. These weigh about 3,000 lb (1,700 kg) when full and are generally 30 in. (0.76 m) in diameter and 80 in. (2.03 m) long.

Ton Container

Any device that is used to add chlorine to the water.

Chlorinator

The portion of the chlorination system that feeds the chlorine solution into a pipe under pressure.

Injector

(1) A section of perforated pipe or porous plates used to inject a gas, such as carbon dioxide or air, under pressure into water. (2) A type of pump.

Diffuser

A heating device used to convert liquid chlorine to chlorine gas.

Chlorine Evaporator

Chlorination using solutions of calcium and sodium hypochlorite.

Hypochlorination

A study using a substance that can be readily identified in water (such as dye) to determine the distribution and rate of flow in a basin, pipe, or channel.

Tracer Study

A single water sample collected at one time from a single point.

Grab Sample

The oxygen dissolved in water, wastewater, or other liquid, usually expressed in milligrams per liter, parts per million, or percent of saturation.

Dissolved Oxygen (DO)

A series of individual grab samples taken at different times from the same sampling point and mixed together.

Composite Sample

A collected sample that accurately reflects the composition of the water to be tested.

Representative Sample

A written record of a sample's history from time of collection to the time of analysis and subsequent disposal.

Chain of Custody

A hydraulic condition, caused by the difference in pressures, in which nonpotable water or other fluids flow into a potable water system.

Backflow

A condition in which a pump, boiler, or other equipment produces a pressure greater than the water supply pressure.

Backpressure

A condition in which the pressure in the distribution system is less than atmospheric pressure, which allows contamination to enter a water system through a cross-connection.

Backsiphonage

Any arrangement of pipes, fittings, or devices that connects a nonpotable system to a potable water system.

Cross-Connection

Any arrangement of pipes, fittings, or devices that connects a potable water supply directly to a nonpotable source at all times.

Actual Cross-Connection

Any arrangement of pipes, fittings, or devices that indirectly connects a potable water supply to a nonpotable source. This connection may not be present at all times, but is always there potentially.

Potential Cross-Connection

In plumbing, the unobstructed vertical distance through the free atmosphere between: (1) the lowest opening from any pipe or outlet supplying water to a tanks, plumbing fixture, or other container. (2) and the overflow rim of that container.

Air Gap

A mechanical device consisting of two independently operated, spring-loaded check valves with a reduced-pressure zone between the check valves. This device is designed to protect against backpressure and backsiphonage.

Reduced Pressure Zone Backflow Preventer (RPZ)

A mechanical device designed basically the same way as the reduced pressure zone backflow preventer (RPZ), but without a relief valve.

Double Check Valve Backflow Preventer

A mechanical device that allows air into the piping system, thereby preventing backflow that could otherwise be caused by the siphoning action created by a partial vacuum.

Vacuum Breaker

A mechanical device consisting of a float check valve and an air inlet port designed to prevent backsiphonage.

Atmospheric Vacuum Breaker

A device designed to prevent backsiphonage, consisting of two independently operating, spring-loaded check valves and an independently operating, spring loaded air-inlet valve.

Pressure Vacuum Breaker

A map that provides a detailed picture of a portion (section) of the distribution system. It reveals the locations and valving of existing mains, locations of fire hydrants, and locations of active service lines.

Sectional Map

A map showing street names, mains, main sizes, numbered valves, and numbered hydrants for the plat-and-list method of setting up valve maps.

Plat

A mapped record that pinpoints the location of valves throughout the distribution system; generally of the plat-and-list method or intersection type.

Valve-and-Hydrant Map

A method of preparing valve-and-hydrant maps. Plat is the map position, showing mains, valves, and hydrants. List is the text portion, which provides the appropriate information for items on the plat.

Plat-and-List Method

Engineering drawings showing the depth of pipe, pipe location (both horizontal and vertical displacements), and the distance from a reference point.

Plan and Profile Drawings

A computerized system for collecting, storing, and analyzing water system components for which geographic location is an important characteristic.

Automated Mapping/Facility Management/Geographic Information System (AM/FM/GIS)

A space defined by the Occupational Safety and Health Administration (OSHA) as having one or more of the following characteristics: Contains, or has the potential to contain, a hazardous atmosphere; contains a material that has the potential for engulfing an entrant; has an internal configuration such that an entrant could be trapped or asphyxiated by inwardly converging walls or by a floor that slopes downward and tapers to a small cross-section; and/or contains any other recognized serious safety or health hazard.

Permit-Required Space

A space defined by the Occupational Safety and Health Administration (OSHA) as not having any of the risks associated with a permit-required space.

Nonpermit-Required Space

The methods and activities employed to promote a favorable relationship with the public.

Public Relations

A US government agency responsible for implementing federal laws designed to protect the environment. Congress has delegated implementation of the Safe Water Drinking Act to this agency.

US Environmental Protection Agency (USEPA)

Nonenforceable health-based goals published along with the promulgation of an MCL. These were originally called Recommended Maximum Contaminant Levels (RMCLs).

Maximum Contaminant Level Goal (MCLG)

The maximum permissible level of a contaminant in water as specified in the regulations of the Safe Drinking Water Act.

Maximum Contaminant Level (MCL)

New chemical compounds that are formed by the reaction of disinfectants with organic compounds in water. At high concentrations, many of these are considered a danger to human health.

Disinfection By-Products (DBPs)

The average of four quarterly samples at each monitoring location to ensure compliance with the Stage 2 DBPR.

Running Annual Average (RAA)

The surface of the water that is contact with the atmosphere.

Free Water Surface

An imaginary surface that coincides with the level of water in an aquifer, or the level to which water in a system would rise in a piezometer.

Piezometric Surface

An instrument for measuring pressure head in a conduit, tank, or soil, by determining the location of the free water surface.

Piezometer

AWWA Water Treatment & Distribution Definitions Grade 1 - 4 Flashcards