Page | 1
CLASS D WATER OPERATOR LICENSE
EXAM TCEQ 2025 BRAND NEW ACTUAL
EXAM WITH ANSWERS.
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 - correct 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 - correct answer -d) all of the above (painting,
cathodic protection, and water stabilization)
, Page | 2
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 - correct 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 - correct answer -a) 50 mg/L
A common chemical used for disinfecting a small public water
supply is:
a) soda ash
b) copper sulfate
c) sodium hypochlorite
d) fluoride
, Page | 3
e) sodium chloride - correct answer -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 - correct 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 - correct answer -d) 2.3
Your ground storage tank is 15 feet high and 30 feet in diameter.
About how much water can it hold?
, Page | 4
a) 31,700 gallons
b) 79,270 gallons
c) 50, 490 gallons
d) 25,150 gallons
e) 10,600 gallons - correct 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 - correct answer -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
e) all of the above - correct answer -e) all of the above
CLASS D WATER OPERATOR LICENSE
EXAM TCEQ 2025 BRAND NEW ACTUAL
EXAM WITH ANSWERS.
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 - correct 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 - correct answer -d) all of the above (painting,
cathodic protection, and water stabilization)
, Page | 2
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 - correct 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 - correct answer -a) 50 mg/L
A common chemical used for disinfecting a small public water
supply is:
a) soda ash
b) copper sulfate
c) sodium hypochlorite
d) fluoride
, Page | 3
e) sodium chloride - correct answer -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 - correct 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 - correct answer -d) 2.3
Your ground storage tank is 15 feet high and 30 feet in diameter.
About how much water can it hold?
, Page | 4
a) 31,700 gallons
b) 79,270 gallons
c) 50, 490 gallons
d) 25,150 gallons
e) 10,600 gallons - correct 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 - correct answer -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
e) all of the above - correct answer -e) all of the above
