Water Quality Flashcards
Geologic strata able to yield water.
- Aquifer
Causes of “red water” complaints
- Corrosion of iron based pipe (ductile iron, galvanized, steel, etc.)
- Growth of iron bacteria
This increases the amount of soap required to make suds.
Hardness
This must be present for corrosion to occur.
Oxygen
Maximum density of water occurs at this temperature.
4 C or 39.2 F
Problem associated with hydrogen sulfide in drinking water.
Rotten egg odor
Used to measure turbidity in drinking water.
Neophelometer
Secondary MCL’s for Iron.
0.3 mg/L
Secondary MCL’s for Manganese.
0.05 mg/L
Problems associated with hard water.
- Extra soap or detergent required to produce suds.
- Soap rings left on fixtures; soap scum left on clothing.
- Deposits of scale in pipes, water heaters, etc.
- Scale deposits on fixtures.
Negative log of the hydrogen ion concentration.
pH
The carrying capacity of iron pipe can be reduced due to the formation of this corrosion by-product.
Tubercules
Light scattering matter in water (suspended particles in water).
Turbidity
Excess carbon dioxide in water can cause this problem
Corrosive or aggressive water
Microorganism that can grow in the presence or absence of oxygen.
Facultative anaerobe
Appearance of deposits left by calcium and magnesium in water.
Chalky white
Appearance of deposits left by iron in water.
Reddish brown-“rust” color
Appearance of deposits left by manganese.
Dark purple to black
Difference in the pH and/or mineral content of drinking water in different communities can cause this problem.
“Travelers Diarrhea” normally short-lived intestinal upset
Organic matter matter exposed to chlorine can produce this chemical in drinking water
Total Trihalomethane, TTHM
The pH scale
0-14
These tests require grab samples that are analyzed immediately.
- Chlorine residuial
- pH
- Temperature
- Dissolved oxygen
Used to determine the corrosive or aggressive characteristics of water.
- Langlier Stability Index (LSI)
- Coupon Test
Corrosion caused by contact of two dissimilar metals.
Galvanic corrosion
This can be added to water in controlled amounts to prevent tooth decay.
Fluoride
These conditions contribute to the corrosive nature of water.
- Dissolved oxygen
- Low pH
- Low alkalinity
- Soft water
- High water temperature
- Excess free CO2
Hydrogen sulfide smell.
Rotten egg smell
Disease causing.
Pathogenic
Waterborne diseases.
- Dysentery
- Typhoid
- Cholera
- Gastroenteritis
- Polio
- Hepatitis A
- Giardiasis
- Cryptosporidiosis
The casing of a water well is grouted for this reason.
To prevent the contamination of the well
Taste and odor is not as noticeable with this condition.
Cold water
Chemical used to control algae in lakes and open reservoirs.
Copper sulfate or Bluestone
This increases the solubility of oxygen in water
Cold water
Indications of pH values: pH below 7
Acidic
Indications of pH values: pH above 7
Alkaline or Basic
Indications of pH values: pH 7
Neutral
Factors that determine the amount of water that can be extracted from an aquifer.
- Thickness of the aquifer
- Permeability of the aquifer
Sacrificial anode used to provide cathodic protection of steel pipes and tanks.
Magnesium or Zinc
Chemicals that raise the pH of water.
- Hydrated lime
- Soda ash
- Caustic soda
This can be used to keep iron and manganese in solution
Poly-phosphates
Scale deposits in pipes are caused by this.
Insoluble carbonate compounds
Anaerobic conditions in deep wells or at the bottom of deep reservoirs can cause this to occur.
The release of iron and manganese into the water
Large amounts of these ions in water can foul an ion exchange resin bed.
Iron and manganese
Most common method of softening water.
- Lime-soda precipitation
- Ion exchange
Secondary MCL’s: Hardness
250mg/L
Secondary MCL’s: Chloride
250mg/L
Secondary MCL’s: Sulfate
250mg/L
Secondary MCL’s: Total dissolved solids
500mg/L
Bacteria that may be associated with “red water.”
The iron bacteria Crenthrix
Most common chemical added to water to prevent corrosion.
Lime
Chemicals that tend to lower pH of water.
- Alum
- Chloride
- Carbon dioxide
Langlier Stability Index (LSI) =
(pH)-(pH saturation)
Indications of the Langlier Stability Index (LSI)
Negative LSI
Corrosive water
Indications of the Langlier Stability Index (LSI)
Positive LSI
Scale forming water
Indications of the Langlier Stability Index (LSI)
LSI = zero
Chemically stable water
This will corrode due to galvanic action when iron pipe and copper pipe are connected.
The iron pipe will corrode
This material provides “cathodic protection” to galvanized iron pipe.
Zinc coating
Lead and copper are introduced into drinking water primarily as a result of this.
Corrosion of plumbing materials
Plumbing materials that may contribute to lead in drinking water.
- Lead based solder used on copper plumbing
- Brass and chrome plated brass faucets
- Galvanized (zinc plated) pipes and fittings
- Lead service pigtails
NTU stand for this.
Nephelometric Turbidity Unit
The most common coagulant used in drinking water treatment.
Aluminum sulfate or “Alum”
Light scattering particles of organic material and clay.
Turbidity
Sources of taste and odor in drinking water.
- Dissolved minerals and gasses (groundwater)
- Algae and bacteria (surface water)
- Industrial wastes (surface and groundwater)
- Decayed vegetation (surface water)
Turbidity in water is present in this form.
Colloidal suspension
Iron at or above this level can cause staining of fixtures and clothing or give a rusty off taste.
0.3 mg/L
Three tastes that can be detected by the tongue.
- Sweet
- Bitter
- Salty
A measure of the intensity of odor in drinking water.
Threshold odor test
Color may be present in these two forms of water.
- Dissolved organic material, called true color (True color is the color that remains after the sample has been filtered to remove suspended particles)
- Suspended collodial particles, which contribute to the apparent color of the water.
Temporary cloudiness in recently drawn water samples may be caused by this.
Air
Free carbon dioxide in water can create this problem.
Corrosion
Water suitable for drinking.
Potable
Per capita water consumption per day
50-150 gallons per person per day