Water Distribution Terms

Question 0

Altitude Valve

Answer 0

A valve that automatically shuts off the flow into an elevated tank when the water level in the tank reaches a predetermined level. The valve automatically opens when the pressure in the distribution system drops below the pressure in the tank.

Question 1

Air Gap

Answer 1

An open, vertical drop in between drinking water supply and potentially contaminated water. This gap prevents the transmission of drinking water by backsiphonage because there is no way potentially contaminated water can reach the drinking water supply.

Question 2

Anode

Answer 2

The positive pole or electrode of an electrolytic system, such as a battery. The anode attracts negatively charged particles or ions (anions).

Question 3

Available Chlorine

Answer 3

A measure of the amount of chlorine available in chlorinated lime, hypochlorite compounds, and other materials that are used as a source of chlorine when compared with that of elemental (liquid or gas) chlorine.

Question 4

Average Demand

Answer 4

The total demand for water during a period of time divided by the number of days in that time period. This is also called the average daily demand.

Question 5

Backflow

Answer 5

A reverse flow condition, created by a difference in water pressures, that causes water to flow back into the distribution pipes of a potable water supply from any source or sources other than the intended source.

Question 6

Backsiphonage

Answer 6

A form of backflow caused by a negative or below atmospheric pressure with a water system.

Question 7

Breakpoint Chlorination

Answer 7

Addition of chlorine to water or wastewater until the chlorine demand has been satisfied. At this point, further additions of chlorine will result in a free chlorine residual that is directly proportional to amount of chlorine added beyond the breakpoint.

Question 8

Cathode

Answer 8

The negative pole or electrode of an electrolytic cell or system. The cathode attracts positively charged particles or ions (cations).

Question 9

Cathodic Protection

Answer 9

An electrical system for the prevention of rust, corrosion, and pitting of metal surfaces that are in contact with water, wastewater, or soil. A low-voltage current is made to flow through a liquid (water) or a soil with contact in contact with a metal in such a manner that the external electromotive force renders the metal structure cathodic. This concentrates corrosion on auxiliary anodic parts which are deliberately allowed to corrode instead of letting the structure corrode.

Question 10

Centrifugal Pump

Answer 10

A pump consisting of an impeller fixed on a rotating shaft that is enclosed in a casing, and having an inlet and discharge connection. As the rotating impeller whirls the liquid around, centrifugal force builds up enough pressure to force the water through the discharge outlet.

Question 11

Chlorine Residual

Answer 11

The concentration of chlorine present in water after the chlorine demand has been satisfied. The concentration is expressed in terms of the total chlorine residual, which includes both free and combined or chemically bound chlorine residuals. Also called Residual Chlorine.

Question 12

Coliform

Answer 12

A group of bacteria found in the intestines of warm-blooded animals (including humans) and also in plants, soil, air, and water. The presence of coliform bacteria is an indicator that the water is polluted and may contain pathogenic (disease-carrying) organisms. Fecal coliforms are those coliforms found in feces of various warm-blooded animals, whereas the term “coliform” also includes other environmental sources.

Question 13

Cross-Connection

Answer 13

(1) A connection between a drinking (potable) water system and an unapproved water supply.
(2) A connection between a storm drain system and a sanitary collection system.
(3) Less frequently used to mean a connection between two sections of a collection system to handle anticipated overloads of one system.

Question 14

Electromotive Force (EMF)

Answer 14

The electrical pressure available to cause a flow of current (amperage) when an electric circuit is closed. Also called voltage.

Question 15

Float on System

Answer 15

A method of operating a water storage facility. Daily flow into a facility is approximately equal to the average daily demand for water. When consumer demands for water are low, the storage facility will be filling. During periods of high demand, the facility will be emptying.

Question 16

Foot Valve

Answer 16

A special type of check valve located at the bottom end of the suction pipe on a pump. This valve opens when the pump operates to allow water to enter the pipe but closes when the pump shuts off to prevent water from flowing out of a suction pipe.

Question 17

Ion

Answer 17

An electrically charged atom, radical, or molecule formed by a loss or gain of one more electrons.

Question 18

Nameplate

Answer 18

A durable, metal plate found on equipment that lists critical installation and operating conditions for the equipment.

Question 19

PCBs

Answer 19

Polychlorinated biphenyls. A class of organic compounds that cause adverse health effects in domestic water supplies.

Question 20

Peak Demand

Answer 20

The maximum momentary load placed on a water treatment plant, pumping station, or distribution system. This demand is usually the maximum average load in one hour or less, but may be specified as the instantaneous load or the load during some other short time period.

Question 21

Positive Bacteriological Sample

Answer 21

A water sample in which gas is produced by coliform during incubation in the multiple tube fermentation test.

Question 22

Prime

Answer 22

The action of filling a pump casing with water to remove the air. Most pumps must be primed before start-up or they will not pump out any water.

Question 23

Residual Chlorine

Answer 23

The concentration of chlorine present in water after the chlorine demand has bern satisfied. The concentration is expressed in terms of the total chlorine residual, which includes both the free and combined or chemically bound chlorine residuals. Also called Chlorine Residual.

Question 24

Set Point

Answer 24

The position at which the control or controller is set. This is the same as the desired value of the process variable. For example, a thermostat is set to maintain a desired temperature.

Question 25

Stale Water

Answer 25

Water that has not flowed recently and may have picked up tastes and odors from distribution lines or storage facilities.

Question 26

Turbidity

Answer 26

Turbidity units are a measure of the cloudiness of water. NTUs are units for instrument-measured (nephelometric) light-deflecting procedures. JTUs are units for visually measured methods. There is no real connection between NTUs and JTUs.

Question 27

Voltage

Answer 27

The electrical pressure available to cause a flow of current (amperage) when an electrical circuit is closed. Also called electromotive force (EMF).

Question 28

Water Hammer

Answer 28

The sound like someone hammering on a pipe that occurs when a valve is opened or closed very rapidly. When a valve position is changed quickly, the water pressure in a pipe will increase and decrease back-and-forth very quickly. The rise and fall in pressures can cause serious damage to the system.

Question 29

Appurtence

Answer 29

Machinery, appliances, structures, and other parts of the main structure necessary to allow it to operate as intended, but not considered part of the main structure.

Question 30

Advanced Metering infrastructure (AMI)

Answer 30

Refers to a system that measures, collects, and analyzes energy usage while interacting with advanced devices such as water meters through various communication media, either on demand or on predefined schedules.