Class D Water License – Texas Exam 2025–2026
Accurate Real Exam Questions and Verified
Correct Answers JUST RELEASED
In Texas, water operator licensing is administered by the _____. - answer>>>TCEQ
Each water sample is tested for all waterborne diseases. (true/false) - answer>>>false (not
all)
Water samples are tested for microorganisms that indicate _____ contamination. -
answer>>>fecal contamination
The total coliform group of viruses are the indicators of fecal contamination. (true/false) -
answer>>>false (bacteria, not viruses)
Fecal coliform live in the _____ of humans and warm-blooded animals. -
answer>>>intestines
The presence of fecal coliform in a water sample indicates intestinal waste is in the
sample, but there is no risk of disease. (true/false) - answer>>>false
The number of water taps served by the system determines the minimum number of
bacteriological samples. (true/false) - answer>>>false (the population determines the
number)
,The purpose of the sample siting plan is to assure bacteriological samples are taken from
vacant houses. (true/false) - answer>>>false (vacant houses are not ideal sampling sites as
they may sit empty for long amounts of time)
_____ is put into bacteriological sample bottles to dechlorinate the water. -
answer>>>Sodium thiosulfate
Before taking a bacteriological sample, you should _____. - answer>>>flush the service
line
The bacteriological sample bottle should be completely filled with sample water.
(true/false) - answer>>>false (only fill 100 ml unless the lab tells you otherwise)
The monthly bacteriological sample should be marked "construction." (true/false) -
answer>>>false (it should be marked routine)
Get bacteriological samples to the lab within _____ hours or they are rejected. -
answer>>>30
It is possible to have positive bacteriological samples removed from your record.
(true/false) - answer>>>true
It is _____ public health risk if a positive fecal coliform repeat sample or a positive total
coliform repeat sample follows a positive fecal coliform routine sample. - answer>>>an
acute
,Acute violations require public notification within 72 hours by radio and television using
the words "Minor Health Concern." (true/false) - answer>>>false (it's a major health
concern)
In the event of low distribution pressure (below _____ psi), water outages, repeated
unacceptable microbiological samples, or failure to maintain adequate chlorine residuals,
special precautions must be instituted by the water system. - answer>>>20 psi
In Texas, all public water systems are required to have ________ facilities.
a. ozonation
b. chlorination
c. softening
d. trihalomethane - answer>>>b. chlorination
Chlorination is the most important process in the production of ________ water. -
answer>>>potable
Besides disinfection, chlorine is used for taste and odor control and ________.
a. oxidation of iron and manganese
b. oxidation of hydrogen sulfide
c. disinfection of repairs
d. all listed - answer>>>d. all listed
Sodium hypochlorite is liquid ________. - answer>>>bleach
Bleach used in public water systems must be ________ approved. - answer>>>NSF
, Calcium hypochlorite is made by reacting chlorine with ________. - answer>>>lime
Calcium hypochlorite will cause explosions or fires if it contacts ________ material. -
answer>>>organic
At room temperature, chlorine gas is greenish-yellow, has a pungent odor, is ________
times heavier than air. - answer>>>2.5
The maximum sustained gas withdrawal rate from 150-lb. cylinders (vacuum
transmission) is ________ lb(s)./day per degree F. - answer>>>1 lbs/day
Disinfection capacity for drinking water must be ________% greater than the highest
expected dosage. - answer>>>50%
Small water systems often use ________ to disinfect their water supply. -
answer>>>hypochlorinators
Hypochlorinators consist of a mixing tank, water, ________ hypochlorite, or ________
hypochlorite and a chemical pump. - answer>>>sodium hypochlorite
calcium hypochlorite
Gas chlorinators use a rotameter to meter chlorine in ________ or grams/hr. -
answer>>>lbs/day
Dosage is the amount of chemical applied, demand is the amount of chemical used up,
________ is the amount of chemical remaining after reacting with demand. -
answer>>>residual
Accurate Real Exam Questions and Verified
Correct Answers JUST RELEASED
In Texas, water operator licensing is administered by the _____. - answer>>>TCEQ
Each water sample is tested for all waterborne diseases. (true/false) - answer>>>false (not
all)
Water samples are tested for microorganisms that indicate _____ contamination. -
answer>>>fecal contamination
The total coliform group of viruses are the indicators of fecal contamination. (true/false) -
answer>>>false (bacteria, not viruses)
Fecal coliform live in the _____ of humans and warm-blooded animals. -
answer>>>intestines
The presence of fecal coliform in a water sample indicates intestinal waste is in the
sample, but there is no risk of disease. (true/false) - answer>>>false
The number of water taps served by the system determines the minimum number of
bacteriological samples. (true/false) - answer>>>false (the population determines the
number)
,The purpose of the sample siting plan is to assure bacteriological samples are taken from
vacant houses. (true/false) - answer>>>false (vacant houses are not ideal sampling sites as
they may sit empty for long amounts of time)
_____ is put into bacteriological sample bottles to dechlorinate the water. -
answer>>>Sodium thiosulfate
Before taking a bacteriological sample, you should _____. - answer>>>flush the service
line
The bacteriological sample bottle should be completely filled with sample water.
(true/false) - answer>>>false (only fill 100 ml unless the lab tells you otherwise)
The monthly bacteriological sample should be marked "construction." (true/false) -
answer>>>false (it should be marked routine)
Get bacteriological samples to the lab within _____ hours or they are rejected. -
answer>>>30
It is possible to have positive bacteriological samples removed from your record.
(true/false) - answer>>>true
It is _____ public health risk if a positive fecal coliform repeat sample or a positive total
coliform repeat sample follows a positive fecal coliform routine sample. - answer>>>an
acute
,Acute violations require public notification within 72 hours by radio and television using
the words "Minor Health Concern." (true/false) - answer>>>false (it's a major health
concern)
In the event of low distribution pressure (below _____ psi), water outages, repeated
unacceptable microbiological samples, or failure to maintain adequate chlorine residuals,
special precautions must be instituted by the water system. - answer>>>20 psi
In Texas, all public water systems are required to have ________ facilities.
a. ozonation
b. chlorination
c. softening
d. trihalomethane - answer>>>b. chlorination
Chlorination is the most important process in the production of ________ water. -
answer>>>potable
Besides disinfection, chlorine is used for taste and odor control and ________.
a. oxidation of iron and manganese
b. oxidation of hydrogen sulfide
c. disinfection of repairs
d. all listed - answer>>>d. all listed
Sodium hypochlorite is liquid ________. - answer>>>bleach
Bleach used in public water systems must be ________ approved. - answer>>>NSF
, Calcium hypochlorite is made by reacting chlorine with ________. - answer>>>lime
Calcium hypochlorite will cause explosions or fires if it contacts ________ material. -
answer>>>organic
At room temperature, chlorine gas is greenish-yellow, has a pungent odor, is ________
times heavier than air. - answer>>>2.5
The maximum sustained gas withdrawal rate from 150-lb. cylinders (vacuum
transmission) is ________ lb(s)./day per degree F. - answer>>>1 lbs/day
Disinfection capacity for drinking water must be ________% greater than the highest
expected dosage. - answer>>>50%
Small water systems often use ________ to disinfect their water supply. -
answer>>>hypochlorinators
Hypochlorinators consist of a mixing tank, water, ________ hypochlorite, or ________
hypochlorite and a chemical pump. - answer>>>sodium hypochlorite
calcium hypochlorite
Gas chlorinators use a rotameter to meter chlorine in ________ or grams/hr. -
answer>>>lbs/day
Dosage is the amount of chemical applied, demand is the amount of chemical used up,
________ is the amount of chemical remaining after reacting with demand. -
answer>>>residual
