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TCEQ CLASS C WATER LICENSE EXAM
|VERIFIED 150Qs&As|NEW
UPDATE|TCEQ EXAM PREP
2026|A+GRADE
1. What is the maximum contaminant level (MCL) for total
coliform bacteria in a public water system under TCEQ rules?
a) 5% of samples per month
b) 1 sample positive per month
c) 0% positive samples (for systems collecting ≥40
samples/month)
d) 10% positive samples
Answer: c) 0% positive samples (for systems collecting ≥40
samples/month)
Rationale: Under the Revised Total Coliform Rule (RTCR), any
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system collecting ≥40 samples/month must have no more than
5% positive for total coliform. However, for Class C systems
(typically small plants), zero tolerance is the operational goal.
But by rule: ≥40 samples → ≤5% positive; <40 samples → no
more than 1 positive. The exam often tests the stricter "zero" for
routine compliance.
2. A water sample tests positive for E. coli. What is the
required action?
a) Collect a repeat sample within 24 hours
b) Issue a boil water notice within 24 hours
c) Collect 3 repeat samples within 24 hours and notify TCEQ
within 24 hours
d) Nothing, unless two consecutive positives occur
Answer: c) Collect 3 repeat samples within 24 hours and
notify TCEQ within 24 hours
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Rationale: An E. coli positive is an acute violation. The system must
collect 3 repeat samples (same day as notification, ideally within
24 hours), notify TCEQ immediately, and inform the public via a
boil water notice.
3. Under the Surface Water Treatment Rules (SWTR), what is
the required log reduction for Giardia lamblia for a
conventional treatment plant?
a) 2-log (99%)
b) 3-log (99.9%)
c) 4-log (99.99%)
d) 6-log (99.9999%)
Answer: b) 3-log (99.9%)
Rationale: SWTR mandates 3-log removal/inactivation of
Giardia and 4-log for viruses. Conventional treatment
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(coag/floc/sed/filt) typically achieves 2.5-log Giardia, so
disinfection must add the rest.
4. Which of the following is a Primary MCL violation?
a) Turbidity >0.3 NTU
b) Chlorine residual of 0.1 mg/L at the far end of the system
c) Arsenic at 0.012 mg/L
d) pH of 8.5
Answer: c) Arsenic at 0.012 mg/L
Rationale: Primary MCL for arsenic is 0.010 mg/L (10 ppb).
Exceeding that is a health-based violation. Turbidity (secondary),
low chlorine (treatment technique), pH (secondary) are not
primary.
5. How often must a Class C surface water plant operator
perform a visible inspection of the treatment facility?
TCEQ CLASS C WATER LICENSE EXAM
|VERIFIED 150Qs&As|NEW
UPDATE|TCEQ EXAM PREP
2026|A+GRADE
1. What is the maximum contaminant level (MCL) for total
coliform bacteria in a public water system under TCEQ rules?
a) 5% of samples per month
b) 1 sample positive per month
c) 0% positive samples (for systems collecting ≥40
samples/month)
d) 10% positive samples
Answer: c) 0% positive samples (for systems collecting ≥40
samples/month)
Rationale: Under the Revised Total Coliform Rule (RTCR), any
,Page 2 of 60
system collecting ≥40 samples/month must have no more than
5% positive for total coliform. However, for Class C systems
(typically small plants), zero tolerance is the operational goal.
But by rule: ≥40 samples → ≤5% positive; <40 samples → no
more than 1 positive. The exam often tests the stricter "zero" for
routine compliance.
2. A water sample tests positive for E. coli. What is the
required action?
a) Collect a repeat sample within 24 hours
b) Issue a boil water notice within 24 hours
c) Collect 3 repeat samples within 24 hours and notify TCEQ
within 24 hours
d) Nothing, unless two consecutive positives occur
Answer: c) Collect 3 repeat samples within 24 hours and
notify TCEQ within 24 hours
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Rationale: An E. coli positive is an acute violation. The system must
collect 3 repeat samples (same day as notification, ideally within
24 hours), notify TCEQ immediately, and inform the public via a
boil water notice.
3. Under the Surface Water Treatment Rules (SWTR), what is
the required log reduction for Giardia lamblia for a
conventional treatment plant?
a) 2-log (99%)
b) 3-log (99.9%)
c) 4-log (99.99%)
d) 6-log (99.9999%)
Answer: b) 3-log (99.9%)
Rationale: SWTR mandates 3-log removal/inactivation of
Giardia and 4-log for viruses. Conventional treatment
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(coag/floc/sed/filt) typically achieves 2.5-log Giardia, so
disinfection must add the rest.
4. Which of the following is a Primary MCL violation?
a) Turbidity >0.3 NTU
b) Chlorine residual of 0.1 mg/L at the far end of the system
c) Arsenic at 0.012 mg/L
d) pH of 8.5
Answer: c) Arsenic at 0.012 mg/L
Rationale: Primary MCL for arsenic is 0.010 mg/L (10 ppb).
Exceeding that is a health-based violation. Turbidity (secondary),
low chlorine (treatment technique), pH (secondary) are not
primary.
5. How often must a Class C surface water plant operator
perform a visible inspection of the treatment facility?
