Water distribution exam #1 ( D1-D2) UPDATED ACTUAL Questions and
CORRECT Answers
Question: What is static head?
Correct Answer: The vertical distance between a reference point to the water surface, when the water us
not moving.
Question: How long must water remain stagnant and undisturbed in the pipe before a first draw down
sample is collected for lead and copper analysis?
Correct Answer: At least 6 hours.
Question: If at least 40 samples per month are collected from a public water system, what is the minimum
percentage of routine/repeat samples that must test negative for total coliform?
Correct Answer: 95%
Question: If the water has low pH, what does that indicate?
Correct Answer: Corrosive water
Question: What is the purpose of a mechanical seal?
Correct Answer: To prevent water leakage from the pump
Question: What could cause a chlorine gas cylinder to frost?
Correct Answer: Feed rate is too high
Question: Which chemicals are formed when chlorine gas is injected into water?
Correct Answer: Hypochlorous acid and hydrochloric acid
Question: Which of the following is true about the effectiveness of chlorine?
Correct Answer: The lower pH, the better disinfection with chlorine
Question: What does a high C factor for a pipe indicate?
Correct Answer: Smooth pipe interior
Question: What is a disadvantage of having a tree formation in the water distribution system
Correct Answer: Dead-end mains
Question: If chlorine is injected into cold water, how would the cold temperature affect the effectiveness of
chlorine?
Correct Answer: More contact time would be required
Question: If a confined space has 20.9% oxygen content, what does this tell you?
Correct Answer: Confined space is safe to enter
Question: What could be the problem if an excessive amount of water is leaking from the stuffing box?
Correct Answer: Packing may need to be replaced, or the packing gland may need to be tightened
Question: What is installed on the suction pipe of a pump to prevent water from draining out of the pump,
and towards the suction pipe?
, Correct Answer: Foot valve
Question: What problem would arise due to excessive air bubbles in a pipeline
Correct Answer: Air pocket forms at the high points
Question: What is formed when chlorine reacts with ammonia?
Correct Answer: Chloramine
Question: What is the disadvantage of using ozone for disinfection?
Correct Answer: Lack of disinfectant residuals
Question: Which water source is the most protected from pathogens
Correct Answer: Deep well ( ground water )
Question: What is used to restrict leakage from the impeller discharge to the pump suction?
Correct Answer: Wear rings
Question: What is Trihalomethane?
Correct Answer: Disinfection by-product
Question: What is the recommended minimum flushing velocity?
Correct Answer: 2.5 ft/s ( 5 ft/s preferred )
Question: What is monochloramine?
Correct Answer: Combined chlorine
Question: What is the most power disinfectant?
Correct Answer: Chlorine
Question: What is the advantage of a compound meter?
Correct Answer: It's capable of measuring a wide range of flow
Question: What is a positive displacement pump?
Correct Answer: Piston pump or gear pump
Question: Where is the best place to install a chlorine gas leak warning device ( not the chlorine sensor )?
Correct Answer: Outside the chlorine gas room
Question: What is one of the purposes of seal water in a pump?
Correct Answer: Cool and lubricate the packings
Question: What would most likely cause a coupon to lose weight?
Correct Answer: Corrosive water
Question: Where is the location of the auxiliary valve on a wet barrel hydrant?
Correct Answer: Between the hydrant & water main
Question: What is used to control water hammer?
Correct Answer: Surge tank
CORRECT Answers
Question: What is static head?
Correct Answer: The vertical distance between a reference point to the water surface, when the water us
not moving.
Question: How long must water remain stagnant and undisturbed in the pipe before a first draw down
sample is collected for lead and copper analysis?
Correct Answer: At least 6 hours.
Question: If at least 40 samples per month are collected from a public water system, what is the minimum
percentage of routine/repeat samples that must test negative for total coliform?
Correct Answer: 95%
Question: If the water has low pH, what does that indicate?
Correct Answer: Corrosive water
Question: What is the purpose of a mechanical seal?
Correct Answer: To prevent water leakage from the pump
Question: What could cause a chlorine gas cylinder to frost?
Correct Answer: Feed rate is too high
Question: Which chemicals are formed when chlorine gas is injected into water?
Correct Answer: Hypochlorous acid and hydrochloric acid
Question: Which of the following is true about the effectiveness of chlorine?
Correct Answer: The lower pH, the better disinfection with chlorine
Question: What does a high C factor for a pipe indicate?
Correct Answer: Smooth pipe interior
Question: What is a disadvantage of having a tree formation in the water distribution system
Correct Answer: Dead-end mains
Question: If chlorine is injected into cold water, how would the cold temperature affect the effectiveness of
chlorine?
Correct Answer: More contact time would be required
Question: If a confined space has 20.9% oxygen content, what does this tell you?
Correct Answer: Confined space is safe to enter
Question: What could be the problem if an excessive amount of water is leaking from the stuffing box?
Correct Answer: Packing may need to be replaced, or the packing gland may need to be tightened
Question: What is installed on the suction pipe of a pump to prevent water from draining out of the pump,
and towards the suction pipe?
, Correct Answer: Foot valve
Question: What problem would arise due to excessive air bubbles in a pipeline
Correct Answer: Air pocket forms at the high points
Question: What is formed when chlorine reacts with ammonia?
Correct Answer: Chloramine
Question: What is the disadvantage of using ozone for disinfection?
Correct Answer: Lack of disinfectant residuals
Question: Which water source is the most protected from pathogens
Correct Answer: Deep well ( ground water )
Question: What is used to restrict leakage from the impeller discharge to the pump suction?
Correct Answer: Wear rings
Question: What is Trihalomethane?
Correct Answer: Disinfection by-product
Question: What is the recommended minimum flushing velocity?
Correct Answer: 2.5 ft/s ( 5 ft/s preferred )
Question: What is monochloramine?
Correct Answer: Combined chlorine
Question: What is the most power disinfectant?
Correct Answer: Chlorine
Question: What is the advantage of a compound meter?
Correct Answer: It's capable of measuring a wide range of flow
Question: What is a positive displacement pump?
Correct Answer: Piston pump or gear pump
Question: Where is the best place to install a chlorine gas leak warning device ( not the chlorine sensor )?
Correct Answer: Outside the chlorine gas room
Question: What is one of the purposes of seal water in a pump?
Correct Answer: Cool and lubricate the packings
Question: What would most likely cause a coupon to lose weight?
Correct Answer: Corrosive water
Question: Where is the location of the auxiliary valve on a wet barrel hydrant?
Correct Answer: Between the hydrant & water main
Question: What is used to control water hammer?
Correct Answer: Surge tank
