Pipes
Which pipe is least likely to corrode in aggressive soils?
A. Ductile iron
B. Galvanized steel
C. PVC
D. Cast iron
C. PVC
What causes hardness in water?
A. Chlorine and ozone
B. Iron and manganese
C. Calcium and magnesium
D. Sodium and potassium
C. Calcium and magnesium
This portable test method is commonly used in the field to measure free chlorine residual.
A. Amperometric
B. diethyl-p-phenylenediamine
C. pH
D. Total Coliforms
B. diethyl-p-phenylenediamine
What is the chemical formula for chlorine gas used in disinfection?
A. NaCl
B. HCl
C. Cl₂
D. ClO₂
C. Cl₂
Which valve type is typically used to completely stop or allow flow in a pipe?
A. Gate valve
B. Check valve
C. Pressure reducing valve
D. Air release valve
A. Gate valve
What does C-factor (Hazen-Williams coefficient) indicate about a pipe?
A. Its length
B. Its diameter
C. Its ability to resist corrosion
D. Its internal smoothness affecting flow
D. Its internal smoothness affecting flow
What is a dead-end main, and why is it a concern?
A. A main leading to a fire hydrant; causes loss of chlorine
B. A pipe with no outlet or loop; can cause stagnation and low chlorine residual
C. A pipe with a closed valve; causes high turbidity
D. A section of pipe made from ductile iron
B. A pipe with no outlet or loop; can cause stagnation and low chlorine residual
This dangerous gas is 2.5 times heavier than air and used in pressurized containers for disinfection.
A. Sodium Hypochlorite
B. Hydrogen Sulfide
C. Carbon monoxide
D. Chlorine Gas
D. Chlorine Gas
Which chemical, with the formula Ca(OCl)₂, is often used in solid form for disinfection?
A. Sodium hydroxide
B. Calcium hypochlorite
C. Lime
D. Calcium carbonate
B. Calcium hypochlorite
What is a common disinfectant residual level that must be maintained in a distribution system?
A. 0.02 mg/L
B. 0.2 mg/L
C. 2 mg/L
D. 20 mg/L
B. 0.2 mg/L
Which pipe material can leach lead if disturbed?
A. HDPE
B. PVC
C. Galvanized steel
D. Copper
C. Galvanized Steel
What is the best indicator of bacterial contamination in water?
A. Turbidity
B. Iron concentration
C. Coliform bacteria
D. pH
C. Coliform bacteria
This type of chlorine is formed when chlorine is added to water and reacts with ammonia.
A. Chloramines
B. Ammonium Chlorine
C. Sodium Hypochlorite
D. Chlorine Ammonium
A. Chloramines
This element, symbolized by Mg, contributes to water hardness along with calcium. What is it?
A. Manganese
B. Magnesium
C. Molybdenum
D. Mercury
B. Magnesium
What is the function of a backflow preventer in a distribution system?
A. Increase water pressure
B. Stop water from flowing backward into the main supply
C. Add disinfectant to water
D. Measure flow rate
B. Stop water from flowing backward into the main supply
What is the most common cause of pipe failure in older water systems?
A. Bacteria
B. Vibration
C. Corrosion
D. High pH
C. Corrosion
Which of the following is NOT a primary characteristic of water quality?
A. Color
B. Flow rate
C. pH
D. Turbidity
B. Flow rate
This disinfection byproduct forms when chlorine reacts with natural organic matter in water.
A. Total Trihalomethanes
B. Chloramines
C. Ozone
D. Chlorine Dioxide
A. Total Trihalomethanes
What chemical, with the formula CO₂, is sometimes used to lower pH?
A. Sodium carbonate
B. Carbon dioxide
C. Chlorine dioxide
D. Calcium bicarbonate
B. Carbon dioxide
What type of valve is best suited to regulate flow in a distribution line (not just open/close)?
A. Gate valve
B. Check valve
C. Globe valve
D. Blow-off valve
C. Globe valve
Which pipe material is most flexible and resistant to ground movement?
A. Cast Iron
B. PVC
C. Ductile Iron
D. HDPE (high-density polyethylene)
D. HDPE
What does TDS stand for in water testing?
A. Total Disinfection Strength
B. Total Dry Solids
C. Total Dissolved Solids
D. Total Detergent Saturation
C. Total Dissolved Solids
What is the free available chlorine percentage in Calcium Hypochlorite?
A. 15%
B. 100%
C. 65%
D. 5%
C. 65%
Sodium hypochlorite, used as a liquid disinfectant, has what chemical formula?
A. NaClO
B. NaOCl
C. Ca(OCl)₂
D. NaOH
B. NaOCl
What is the minimum recommended separation distance between a water main and a parallel sanitary sewer (in most codes)?
A. 1 foot
B. 2 feet
C. 10 feet
D. 20 feet
C. 10 feet