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CLASS D WATER OPERATOR LICENSE EXAM
2025| BRAND NEW ACTUAL EXAM WITH
100% VERIFIED QUESTIONS AND CORRECT
SOLUTIONS| GUARANTEED VALUE PACK|
ACE YOUR GRADES.
The plant operator is responsible for a sufficient supply of
safe and ________ drinking water. - ANSWERS_Palatable
The pH of water indicates whether it is acidic or basic and is
expressed by a scale of numbers ranging from:
a) 0 - 7
b) 0 - 14
c) 1 - 7
d) 1 - 14
e) none of the above - ANSWERS_b) 0 - 14
Before a new main is placed into service, it must be properly
disinfected with a minimum chlorine dosage of:
a) 50 mg/L
b) 30 mg/L
c) 40 mg/L
d) 75 mg/L
e) 25 mg/L - ANSWERS_a) 50 mg/L
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A common chemical used for disinfecting a small public
water supply is:
a) soda ash
b) copper sulfate
c) sodium hypochlorite
d) fluoride
e) sodium chloride - ANSWERS_c) sodium hypochlorite
Gravity filters will remove which of the following from
surface water supplies:
a) turbidity
b) taste and odors
c) nitrates
d) hardness
e) chlorides - ANSWERS_a) turbidity
If you added 3.5 mg/L of chlorine to your storage tank and 30
minutes later measured the residual at 1.2 mg/L, what was the
chlorine demand in the tank?
a) 4.2
b) 2.9
c) 0.3
d) 2.3
e) 4.7 - ANSWERS_d) 2.3
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Your ground storage tank is 15 feet high and 30 feet in
diameter. About how much water can it hold?
a) 31,700 gallons
b) 79,270 gallons
c) 50, 490 gallons
d) 25,150 gallons
e) 10,600 gallons - ANSWERS_...
When fecal coliform organisms are found in a water supply, it
is an indication that:
a) the water supply is contaminated
b) pathogenic organisms might be present
c) the water may be unsuitable for drinking
d) follow-up sampling must take place
e) all of the above - ANSWERS_e) all of the above
Which of the following is an acceptable level of residual
chlorine in the far reaches of a distribution system?
a) 0.2 mg/L of free chlorine for a small GWS
b) 0.5 mg/L of chloramine for a large SWS
c) 1.0 mg/L of combined when using ammoniation facilities
d) 1.0 mg/L of total for a large SWS
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e) all of the above - ANSWERS_e) all of the above
The purpose of an air line on a well is to:
a) aerate the well
b) determine the depth of the aquifer
c) inject chlorine into the well
d) allow the well to breathe
e) determine the water level - ANSWERS_e) determine the
water level
The drawdown of a well is determined by:
a) a properly installed air line
b) the difference between the static and pumping level
c) a psi gage calibrated in feet of water
d) a tape measure
e) an electronic sounder - ANSWERS_b) the difference
between the static and pumping level
A common type of oxidant that is used at most SW treatment
plants to kill bacteria and to prevent trihalomethane formation
is:
a) total chlorine
b) combined chlorine
c) chlorine dioxide
CLASS D WATER OPERATOR LICENSE EXAM
2025| BRAND NEW ACTUAL EXAM WITH
100% VERIFIED QUESTIONS AND CORRECT
SOLUTIONS| GUARANTEED VALUE PACK|
ACE YOUR GRADES.
The plant operator is responsible for a sufficient supply of
safe and ________ drinking water. - ANSWERS_Palatable
The pH of water indicates whether it is acidic or basic and is
expressed by a scale of numbers ranging from:
a) 0 - 7
b) 0 - 14
c) 1 - 7
d) 1 - 14
e) none of the above - ANSWERS_b) 0 - 14
Before a new main is placed into service, it must be properly
disinfected with a minimum chlorine dosage of:
a) 50 mg/L
b) 30 mg/L
c) 40 mg/L
d) 75 mg/L
e) 25 mg/L - ANSWERS_a) 50 mg/L
, Page |2
A common chemical used for disinfecting a small public
water supply is:
a) soda ash
b) copper sulfate
c) sodium hypochlorite
d) fluoride
e) sodium chloride - ANSWERS_c) sodium hypochlorite
Gravity filters will remove which of the following from
surface water supplies:
a) turbidity
b) taste and odors
c) nitrates
d) hardness
e) chlorides - ANSWERS_a) turbidity
If you added 3.5 mg/L of chlorine to your storage tank and 30
minutes later measured the residual at 1.2 mg/L, what was the
chlorine demand in the tank?
a) 4.2
b) 2.9
c) 0.3
d) 2.3
e) 4.7 - ANSWERS_d) 2.3
, Page |3
Your ground storage tank is 15 feet high and 30 feet in
diameter. About how much water can it hold?
a) 31,700 gallons
b) 79,270 gallons
c) 50, 490 gallons
d) 25,150 gallons
e) 10,600 gallons - ANSWERS_...
When fecal coliform organisms are found in a water supply, it
is an indication that:
a) the water supply is contaminated
b) pathogenic organisms might be present
c) the water may be unsuitable for drinking
d) follow-up sampling must take place
e) all of the above - ANSWERS_e) all of the above
Which of the following is an acceptable level of residual
chlorine in the far reaches of a distribution system?
a) 0.2 mg/L of free chlorine for a small GWS
b) 0.5 mg/L of chloramine for a large SWS
c) 1.0 mg/L of combined when using ammoniation facilities
d) 1.0 mg/L of total for a large SWS
, Page |4
e) all of the above - ANSWERS_e) all of the above
The purpose of an air line on a well is to:
a) aerate the well
b) determine the depth of the aquifer
c) inject chlorine into the well
d) allow the well to breathe
e) determine the water level - ANSWERS_e) determine the
water level
The drawdown of a well is determined by:
a) a properly installed air line
b) the difference between the static and pumping level
c) a psi gage calibrated in feet of water
d) a tape measure
e) an electronic sounder - ANSWERS_b) the difference
between the static and pumping level
A common type of oxidant that is used at most SW treatment
plants to kill bacteria and to prevent trihalomethane formation
is:
a) total chlorine
b) combined chlorine
c) chlorine dioxide
