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CLASS D WATER OPERATOR LICENSE
EXAM TCEQ |COMPLETE EXAM WITH
QUESTIONS AND CORRECT ANSWERS
2026
At 0.8 - 1.0 mg/L, fluoride reduces dental cavities, but in higher doeses (>2.0
mg/L) can cause _____ of teeth over time. - correct-answer -mottling
T/F: One by-product of chlorinated drinking water is trihalomethane, a suspected
carcinogen. - correct-answer -True
Repeat samples must be taken at (a) the _______ ______ (b) within 5 connections
upstream and (c) within 5 connections downstream. - correct-answer -positive
point
T/F: If you do not fill out the submission form completely, you risk losing credit for
the sample. - correct-answer -True
T/F: The presence of fecal coliform in a water sample indicates fecal
contamination from a human or warm-blooded animal. - correct-answer -True
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The purpose of the sample site plan is to assure bacteriological samples are
collected from ______ service connections which are representative of the
distribution system. - correct-answer -active
T/F: Keep the sample in ice or in a cooler prior to and during lab transport
because heat stimulates bacterial growth. - correct-answer -True
The action level for lead is _______ mg/L and for copper it is _____ mg/L. -
correct-answer -..3
T/F: Low doses of heavy metals such as lead and copper can cause damage to the
central nervous system over time. - correct-answer -True
A certain group of bacteria is used to indicate the possible presence of a
pathogen--- the ________ group. - correct-answer -Coliform
Disinfection is the destruction of disease-causing microorganisms called ______. -
correct-answer -Pathogens
At room temperature chlorine is a greenish-yellow gas that is ___ times heavier
than air. - correct-answer -2.5
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The State requires ________ to be kept in stock for disinfecting new water lines. -
correct-answer -Calcium hypochlorite
T/F: Hypochlorinators consist of a mixing tank and chemical solution feed pump. -
correct-answer -True
A full-face self-contained breathing apparatus or supplied air respirator must be
readily accessible outside the fire station when chlorine gas is used. - correct-
answer -False (A full-face self-contained breathing apparatus (SCBA) or supplied
air respirator that meets OSHA standards shall be readily accessible outside the
*chlorinator room* when chlorine gas is used.)
T/F: All public water systems must have chlorination facilities. - correct-answer -
True
If chlorine enters the eyes, flush with running cool water for at least ___ minutes
and seek medical attention. - correct-answer -15 minutes
Liquid bleach used in PWS must be ______ approved. - correct-answer -NSF
, 4|Page
T/F: Primary components of a gas feed chlorinator include an injector, flowrate
controller, rotameter, and mixing tank. - correct-answer -False (injector, vacuum
regulator, flowrate controller, rotameter- *not a mixing tank*)
The maximum sustained gas withdrawal rate for pressure transmission 150 lb
cylinders is ____ lbs/day - correct-answer -40
T/F: Utility operators use chlorine in three commercial forms:
1) pure chlorine in the liquid or gas state
2) bleach solutions
3) granular/tablet compounds - correct-answer -True
T/F: If chlorine contacts the skin, flush with an emergency shower or garden hose
for at least an hour. - correct-answer -False (15 minutes)
Hypochlorous acid is the disinfectant and the _____ residual. - correct-answer -
Free
If a major chlorine leak occurs, call the supplier and ______. - correct-answer -
TCEQ
CLASS D WATER OPERATOR LICENSE
EXAM TCEQ |COMPLETE EXAM WITH
QUESTIONS AND CORRECT ANSWERS
2026
At 0.8 - 1.0 mg/L, fluoride reduces dental cavities, but in higher doeses (>2.0
mg/L) can cause _____ of teeth over time. - correct-answer -mottling
T/F: One by-product of chlorinated drinking water is trihalomethane, a suspected
carcinogen. - correct-answer -True
Repeat samples must be taken at (a) the _______ ______ (b) within 5 connections
upstream and (c) within 5 connections downstream. - correct-answer -positive
point
T/F: If you do not fill out the submission form completely, you risk losing credit for
the sample. - correct-answer -True
T/F: The presence of fecal coliform in a water sample indicates fecal
contamination from a human or warm-blooded animal. - correct-answer -True
,2|Page
The purpose of the sample site plan is to assure bacteriological samples are
collected from ______ service connections which are representative of the
distribution system. - correct-answer -active
T/F: Keep the sample in ice or in a cooler prior to and during lab transport
because heat stimulates bacterial growth. - correct-answer -True
The action level for lead is _______ mg/L and for copper it is _____ mg/L. -
correct-answer -..3
T/F: Low doses of heavy metals such as lead and copper can cause damage to the
central nervous system over time. - correct-answer -True
A certain group of bacteria is used to indicate the possible presence of a
pathogen--- the ________ group. - correct-answer -Coliform
Disinfection is the destruction of disease-causing microorganisms called ______. -
correct-answer -Pathogens
At room temperature chlorine is a greenish-yellow gas that is ___ times heavier
than air. - correct-answer -2.5
,3|Page
The State requires ________ to be kept in stock for disinfecting new water lines. -
correct-answer -Calcium hypochlorite
T/F: Hypochlorinators consist of a mixing tank and chemical solution feed pump. -
correct-answer -True
A full-face self-contained breathing apparatus or supplied air respirator must be
readily accessible outside the fire station when chlorine gas is used. - correct-
answer -False (A full-face self-contained breathing apparatus (SCBA) or supplied
air respirator that meets OSHA standards shall be readily accessible outside the
*chlorinator room* when chlorine gas is used.)
T/F: All public water systems must have chlorination facilities. - correct-answer -
True
If chlorine enters the eyes, flush with running cool water for at least ___ minutes
and seek medical attention. - correct-answer -15 minutes
Liquid bleach used in PWS must be ______ approved. - correct-answer -NSF
, 4|Page
T/F: Primary components of a gas feed chlorinator include an injector, flowrate
controller, rotameter, and mixing tank. - correct-answer -False (injector, vacuum
regulator, flowrate controller, rotameter- *not a mixing tank*)
The maximum sustained gas withdrawal rate for pressure transmission 150 lb
cylinders is ____ lbs/day - correct-answer -40
T/F: Utility operators use chlorine in three commercial forms:
1) pure chlorine in the liquid or gas state
2) bleach solutions
3) granular/tablet compounds - correct-answer -True
T/F: If chlorine contacts the skin, flush with an emergency shower or garden hose
for at least an hour. - correct-answer -False (15 minutes)
Hypochlorous acid is the disinfectant and the _____ residual. - correct-answer -
Free
If a major chlorine leak occurs, call the supplier and ______. - correct-answer -
TCEQ
