Page 1 of 105
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Texas Class D Water License Latest Update
Exam 2026 Questions And Verified Answers, 100%
Guaranteed Pass
1. In Texas, all public water systems must have which type
of facilities?
a) Filtration
b) Fluoridation
c) Chlorination
d) Softening
Answer: c) Chlorination
Rationale: TCEQ rules (30 TAC 290) require chlorination
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facilities for all public water systems to ensure disinfection and
protect public health.
2. What is the maximum time a Class D license is valid for a
system with 250 connections or less?
a) 1 year
b) 2 years
c) 3 years
d) 5 years
Answer: c) 3 years
Rationale: Unlike higher licenses that renew annually, Class D
licenses for small systems are valid for three years.
3. (Scenario) You are the operator of a rural water supply. A
customer calls and says their water is suddenly "milky"
white. After running the tap for 5 minutes, it clears up from
the bottom up. What is the most likely cause?
a) High iron content
b) Air entrainment (Air in the line)
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c) Chlorine gas leak
d) Sewage contamination
Answer: b) Air entrainment
Rationale: Milky water that clears from the bottom up
indicates tiny air bubbles. This is physical, not chemical, and
usually harmless. Contamination or gas leaks have different
odors/appearances.
4. The federal regulatory agency that sets drinking water
standards is the:
a) TCEQ
b) EPA
c) TWDB
d) OSHA
Answer: b) EPA
Rationale: The Environmental Protection Agency (EPA) sets the
national standards under the Safe Drinking Water Act, while
TCEQ enforces them in Texas.
,Page 2 of 105
Texas Class D Water License Latest Update
Exam 2026 Questions And Verified Answers, 100%
Guaranteed Pass
1. In Texas, all public water systems must have which type
of facilities?
a) Filtration
b) Fluoridation
c) Chlorination
d) Softening
Answer: c) Chlorination
Rationale: TCEQ rules (30 TAC 290) require chlorination
,Page 3 of 105
facilities for all public water systems to ensure disinfection and
protect public health.
2. What is the maximum time a Class D license is valid for a
system with 250 connections or less?
a) 1 year
b) 2 years
c) 3 years
d) 5 years
Answer: c) 3 years
Rationale: Unlike higher licenses that renew annually, Class D
licenses for small systems are valid for three years.
3. (Scenario) You are the operator of a rural water supply. A
customer calls and says their water is suddenly "milky"
white. After running the tap for 5 minutes, it clears up from
the bottom up. What is the most likely cause?
a) High iron content
b) Air entrainment (Air in the line)
, Page 4 of 105
c) Chlorine gas leak
d) Sewage contamination
Answer: b) Air entrainment
Rationale: Milky water that clears from the bottom up
indicates tiny air bubbles. This is physical, not chemical, and
usually harmless. Contamination or gas leaks have different
odors/appearances.
4. The federal regulatory agency that sets drinking water
standards is the:
a) TCEQ
b) EPA
c) TWDB
d) OSHA
Answer: b) EPA
Rationale: The Environmental Protection Agency (EPA) sets the
national standards under the Safe Drinking Water Act, while
TCEQ enforces them in Texas.
