CDPH WATER DISTRIBUTION GRADE 2 QUESTIONS AND
ANSWERS CORRECT 2025-2026
What is static head? - The vertical distance between a reference point to the water surface,
when the water is not moving.
How long must water remain stagnant and undisturbed in the pipe before a first-draw
sample is collected for lead and copper analysis? - At least 6 hours
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? -
95%
If the water has low pH, What does it indicate? - Corrosive water
What is the purpose of a mechanical seal? - Prevents water leakage from the pump
What could cause a chlorine gas cylinder to frost? - Feed rate is too high
Which chemicals are formed when chlorine gas is injected into water? - Hypochlorous acid
and hydrochloric acid
Which of the following is true about the effectiveness of chlorine? A) The higher the pH,
the better the disinfection of chlorine, B) chlorine is the most effective at pH=10, C) the
lower the pH, the better the disinfection of chlorine, or D) chlorine is the most effective at
pH=12. - C) the lower the pH, the better the disinfection of chlorine.
,What does a high C factor for a pipe indicate? - Smooth pipe interior
,What is the disadvantage of having a tree formation in the water distribution system? -
Dead- end mains
If chlorine is injected into cold water, How would the cold temperature affect the
effectiveness of chlorine? - More contact time would be required
If a confined space has 20.9% oxygen content, What does this tell you? - Confined space is
safe to enter
What could be the problem if an excessive amount of water is leaking from the stuffing
box? - Packings may need to be replaced, or the packing gland may need to be tightened.
What is installed on the suction pipe of a pump to prevent water from draining out of the
pump, and towards the suction pipe? - foot valve
What problem could arise due to excessive air bubbles in a pipeline? - air pocket forms at
the high points
What is formed when chlorine reacts with ammonia? - Chloramine
What is the disadvantage of using ozone for disinfection? - lack of disinfectant residuals
Which water source is the most protected from pathogens? - deep well
What is used to restrict leakage from the impeller discharge to the pump suction? - wear
rings
, What is trihalomethane? - Disinfection by-product
What is the recommended minimum flushing velocity? - 2.5 ft/s (5 ft/s preferred)
What is monochloramine? - combined chlorine
Which of the following is the most powerful disinfectant? - chlorine
What is the advantage of a compound meter? - It's capable of measuring a wide range of
flow
Which of the following is a positive displacement pump? - piston pump or gear pump
Where is the best place to install a chlorine gas leak warning device (not the chlorine
sensor)? - Outside the chlorine gas room
What is one of the purposes of seal water in a pump? - cool and lubricate the packings
What would most likely cause a coupon to lose weight? - corrosive water
Where is the location of the auxiliary valve on a wet-barrel hydrant? - between the hydrant
and water main
What is used to control water hammer? - surge tank
ANSWERS CORRECT 2025-2026
What is static head? - The vertical distance between a reference point to the water surface,
when the water is not moving.
How long must water remain stagnant and undisturbed in the pipe before a first-draw
sample is collected for lead and copper analysis? - At least 6 hours
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? -
95%
If the water has low pH, What does it indicate? - Corrosive water
What is the purpose of a mechanical seal? - Prevents water leakage from the pump
What could cause a chlorine gas cylinder to frost? - Feed rate is too high
Which chemicals are formed when chlorine gas is injected into water? - Hypochlorous acid
and hydrochloric acid
Which of the following is true about the effectiveness of chlorine? A) The higher the pH,
the better the disinfection of chlorine, B) chlorine is the most effective at pH=10, C) the
lower the pH, the better the disinfection of chlorine, or D) chlorine is the most effective at
pH=12. - C) the lower the pH, the better the disinfection of chlorine.
,What does a high C factor for a pipe indicate? - Smooth pipe interior
,What is the disadvantage of having a tree formation in the water distribution system? -
Dead- end mains
If chlorine is injected into cold water, How would the cold temperature affect the
effectiveness of chlorine? - More contact time would be required
If a confined space has 20.9% oxygen content, What does this tell you? - Confined space is
safe to enter
What could be the problem if an excessive amount of water is leaking from the stuffing
box? - Packings may need to be replaced, or the packing gland may need to be tightened.
What is installed on the suction pipe of a pump to prevent water from draining out of the
pump, and towards the suction pipe? - foot valve
What problem could arise due to excessive air bubbles in a pipeline? - air pocket forms at
the high points
What is formed when chlorine reacts with ammonia? - Chloramine
What is the disadvantage of using ozone for disinfection? - lack of disinfectant residuals
Which water source is the most protected from pathogens? - deep well
What is used to restrict leakage from the impeller discharge to the pump suction? - wear
rings
, What is trihalomethane? - Disinfection by-product
What is the recommended minimum flushing velocity? - 2.5 ft/s (5 ft/s preferred)
What is monochloramine? - combined chlorine
Which of the following is the most powerful disinfectant? - chlorine
What is the advantage of a compound meter? - It's capable of measuring a wide range of
flow
Which of the following is a positive displacement pump? - piston pump or gear pump
Where is the best place to install a chlorine gas leak warning device (not the chlorine
sensor)? - Outside the chlorine gas room
What is one of the purposes of seal water in a pump? - cool and lubricate the packings
What would most likely cause a coupon to lose weight? - corrosive water
Where is the location of the auxiliary valve on a wet-barrel hydrant? - between the hydrant
and water main
What is used to control water hammer? - surge tank
