Class D Water Operator License Exam TCEQ
Exam 2025–2026 Accurate Real Exam Questions
and Verified Correct Answers JUST RELEASED
A potable water supply:
a) is free of pathogenic organisms
b) has an adequate chlorine residual
c) contains a safe level of chemicals
d) all of the above
e) is found only in community type water systems - answer>>>d) all of the above
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 - answer>>>c) sodium hypochlorite
T/F: In Texas, about 75% of all water is used for commercial, industrial, or agricultural
purposes. - answer>>>True
Which of the following is part of a hypochlorination system?
a) solution feed pump
b) gas cylinder
c) rotameter
d) injector/ejector
e) all of the above - answer>>>a) solution feed pump
,An elevated storage tank should be protected against corrosion by:
a) painting
b) cathodic protection
c) water stabilization
d) all of the above
e) galvanizing - answer>>>d) all of the above (painting, cathodic protection, and water
stabilization)
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 - answer>>>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 - answer>>>a) 50 mg/L
Gravity filters will remove which of the following from surface water supplies:
a) turbidity
, b) taste and odors
c) nitrates
d) hardness
e) chlorides - answer>>>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 - answer>>>d) 2.3
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 - answer>>>...
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 - answer>>>e) all of the above
Exam 2025–2026 Accurate Real Exam Questions
and Verified Correct Answers JUST RELEASED
A potable water supply:
a) is free of pathogenic organisms
b) has an adequate chlorine residual
c) contains a safe level of chemicals
d) all of the above
e) is found only in community type water systems - answer>>>d) all of the above
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 - answer>>>c) sodium hypochlorite
T/F: In Texas, about 75% of all water is used for commercial, industrial, or agricultural
purposes. - answer>>>True
Which of the following is part of a hypochlorination system?
a) solution feed pump
b) gas cylinder
c) rotameter
d) injector/ejector
e) all of the above - answer>>>a) solution feed pump
,An elevated storage tank should be protected against corrosion by:
a) painting
b) cathodic protection
c) water stabilization
d) all of the above
e) galvanizing - answer>>>d) all of the above (painting, cathodic protection, and water
stabilization)
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 - answer>>>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 - answer>>>a) 50 mg/L
Gravity filters will remove which of the following from surface water supplies:
a) turbidity
, b) taste and odors
c) nitrates
d) hardness
e) chlorides - answer>>>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 - answer>>>d) 2.3
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 - answer>>>...
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 - answer>>>e) all of the above
