D1 & D2 PRACTICE EXAM 1 QUESTIONS
WITH CORRECT ANSWERS 2025
What is static head? - CORRECT ANSWER -
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? - CORRECT ANSWER -At least 6 hours
If at least 40 samples per month are collected from a public water system, what is the minimum percent
age of routine/repeat samples that must test negative for total coliform? - CORRECT ANSWER -95%
If the water has low pH, what does it indicate? - CORRECT ANSWER -Corrosive water
What is the purpose of a mechanical seal? - CORRECT ANSWER -Prevents water leakage from the pump
What could cause a chlorine gas cylinder to frost? - CORRECT ANSWER -Feed rate is too high
Which chemicals are formed when chlorine gas is injected into water? - CORRECT ANSWER -
Hypochlorous acid and hydrochloric acid
Which of the following is true about the effectivenessRof chlorine? - CORRECT ANSWER -
The lower the pH, the better the disinfection with chlorine.
What does a high C factor for a pipe indicate? - CORRECT ANSWER -Smooth pipe interior
What is the disadvantage of having a tree formation in the water distribution system! -
CORRECT ANSWER -Dead-end mains
If chlorine is injected into cold water, how would the cold temperature affect the effectiveness of chlorin
e? - CORRECT ANSWER -More contact time would be required
, If a confined space has 20.9% oxygen content, what does this tell you? - CORRECT ANSWER -
Confined space is safe to enter
What could be the problem if an excessive amount of water is leaking from the stuffing box? -
CORRECT ANSWER -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 to
wards the suction pipe? - CORRECT ANSWER -Foot valve
What problem could arise due to excessive air bubbles in a pipeline? - CORRECT ANSWER -
Air pocket forms at the high points
What is formed when chlorine reacts with ammonia? - CORRECT ANSWER -Chloramine
What is the disadvantage of using ozone for disinfection? - CORRECT ANSWER -
Lack of disinfectant residuals
Which water source is the most protected from pathogens? - CORRECT ANSWER -Deep well
What is used to restrict leakage from the impeller discharge to the pump suction? - CORRECT ANSWER -
Wear rings
What is trihalomethane? - CORRECT ANSWER -Disinfection by-product
What is the recommended minimum flushing velocity? - CORRECT ANSWER -2.5 ft/s (5 ft/s preferred)
What is monochloramine? - CORRECT ANSWER -Combined chlorine
Which of the following is the mostRpowerful disinfectant? - CORRECT ANSWER -Chlorine
WITH CORRECT ANSWERS 2025
What is static head? - CORRECT ANSWER -
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? - CORRECT ANSWER -At least 6 hours
If at least 40 samples per month are collected from a public water system, what is the minimum percent
age of routine/repeat samples that must test negative for total coliform? - CORRECT ANSWER -95%
If the water has low pH, what does it indicate? - CORRECT ANSWER -Corrosive water
What is the purpose of a mechanical seal? - CORRECT ANSWER -Prevents water leakage from the pump
What could cause a chlorine gas cylinder to frost? - CORRECT ANSWER -Feed rate is too high
Which chemicals are formed when chlorine gas is injected into water? - CORRECT ANSWER -
Hypochlorous acid and hydrochloric acid
Which of the following is true about the effectivenessRof chlorine? - CORRECT ANSWER -
The lower the pH, the better the disinfection with chlorine.
What does a high C factor for a pipe indicate? - CORRECT ANSWER -Smooth pipe interior
What is the disadvantage of having a tree formation in the water distribution system! -
CORRECT ANSWER -Dead-end mains
If chlorine is injected into cold water, how would the cold temperature affect the effectiveness of chlorin
e? - CORRECT ANSWER -More contact time would be required
, If a confined space has 20.9% oxygen content, what does this tell you? - CORRECT ANSWER -
Confined space is safe to enter
What could be the problem if an excessive amount of water is leaking from the stuffing box? -
CORRECT ANSWER -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 to
wards the suction pipe? - CORRECT ANSWER -Foot valve
What problem could arise due to excessive air bubbles in a pipeline? - CORRECT ANSWER -
Air pocket forms at the high points
What is formed when chlorine reacts with ammonia? - CORRECT ANSWER -Chloramine
What is the disadvantage of using ozone for disinfection? - CORRECT ANSWER -
Lack of disinfectant residuals
Which water source is the most protected from pathogens? - CORRECT ANSWER -Deep well
What is used to restrict leakage from the impeller discharge to the pump suction? - CORRECT ANSWER -
Wear rings
What is trihalomethane? - CORRECT ANSWER -Disinfection by-product
What is the recommended minimum flushing velocity? - CORRECT ANSWER -2.5 ft/s (5 ft/s preferred)
What is monochloramine? - CORRECT ANSWER -Combined chlorine
Which of the following is the mostRpowerful disinfectant? - CORRECT ANSWER -Chlorine
