CLASS D WATER OPERATOR LICENSE EXAM TCEQ EXAM
2026 QUESTIONS AND CORRECT ANSWERS (100%
CORRECT VERIFIED ANSWERS)
The State recommends a TON of ___ or less. - CORRECT ANSWER ✔✔ - 3
T/F: The State recommends 20 color units or less for a quality water. - CORRECT
ANSWER ✔✔ - False (The state recommends 15 units of color or less for drinking
water.)
T/F: Examples of inorganic matter found in water include rock, sand, metals, and
minerals. - CORRECT ANSWER ✔✔ - True
T/F: The red color caused by iron is an example of suspended or apparent color
and it can be removed by filtration. - CORRECT ANSWER ✔✔ - True
Excessive calcium and _____ are the primary cause of hardness in water. -
CORRECT ANSWER ✔✔ - Magnesium
T/F: The State recommends a maximum total dissolved solids content of 500 mg/L
- CORRECT ANSWER ✔✔ - False (The state recommends that TDS not exceed 1000
mg/L)
There are 3 common gases found in water: methane, carbon dioxide, and
__________ ___________. - CORRECT ANSWER ✔✔ - hydrogen sulfide
Pg. 1
,T/F: Turbidity must be limited because it shelters and nourishes bacteria and
interferes with disinfection. - CORRECT ANSWER ✔✔ - True
T/F: Bleach or alcohol require less contact time than flaming to disinfect a faucet.
- CORRECT ANSWER ✔✔ - False (flaming requires less contact time)
T/F: The "primary limits" refer to chemicals with maximum contaminant levels
that can be exceeded. - CORRECT ANSWER ✔✔ - False (refers to chemicals with
maximum contaminant levels (MCLs) that *CANNOT* be exceeded.)
T/F: The term "total coliform" means fecal and non-fecal coliform. - CORRECT
ANSWER ✔✔ - True
T/F: Pathogens are disease-causing microorganisms. - CORRECT ANSWER ✔✔ -
True
If a routine sample is positive, flush the positive sample point, check the chlorine
residual, then resample within 24 days of notification. - CORRECT ANSWER ✔✔ -
False (If a routine sample is total coliform-positive, the PWS should flush the
positive sample point, check the chlorine residual, then resample within *24 hrs*
of notification)
To prevent the formation of THMS in surface water, chlorine is combined with
_____ forming chloramine, combined chlorine residual. - CORRECT ANSWER ✔✔ -
Ammonia
If there is no chlorine ______ at a faucet, do not sample, flush longer. - CORRECT
ANSWER ✔✔ - residual
Pg. 2
, T/F: All repeat samples must be collected on successive days. - CORRECT ANSWER
✔✔ - False (Collect all repeat sample on the same day)
In the event of distribution pressure below ___ psi, _______ outages, repeated
bad samples or chlorine _____ below minimum, special precautions must be
instituted. - CORRECT ANSWER ✔✔ - 20/water/residual
Get the sample to the lab within ___________ or it will be rejected. - CORRECT
ANSWER ✔✔ - 30 hours (for BacT samples)
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
Pg. 3
2026 QUESTIONS AND CORRECT ANSWERS (100%
CORRECT VERIFIED ANSWERS)
The State recommends a TON of ___ or less. - CORRECT ANSWER ✔✔ - 3
T/F: The State recommends 20 color units or less for a quality water. - CORRECT
ANSWER ✔✔ - False (The state recommends 15 units of color or less for drinking
water.)
T/F: Examples of inorganic matter found in water include rock, sand, metals, and
minerals. - CORRECT ANSWER ✔✔ - True
T/F: The red color caused by iron is an example of suspended or apparent color
and it can be removed by filtration. - CORRECT ANSWER ✔✔ - True
Excessive calcium and _____ are the primary cause of hardness in water. -
CORRECT ANSWER ✔✔ - Magnesium
T/F: The State recommends a maximum total dissolved solids content of 500 mg/L
- CORRECT ANSWER ✔✔ - False (The state recommends that TDS not exceed 1000
mg/L)
There are 3 common gases found in water: methane, carbon dioxide, and
__________ ___________. - CORRECT ANSWER ✔✔ - hydrogen sulfide
Pg. 1
,T/F: Turbidity must be limited because it shelters and nourishes bacteria and
interferes with disinfection. - CORRECT ANSWER ✔✔ - True
T/F: Bleach or alcohol require less contact time than flaming to disinfect a faucet.
- CORRECT ANSWER ✔✔ - False (flaming requires less contact time)
T/F: The "primary limits" refer to chemicals with maximum contaminant levels
that can be exceeded. - CORRECT ANSWER ✔✔ - False (refers to chemicals with
maximum contaminant levels (MCLs) that *CANNOT* be exceeded.)
T/F: The term "total coliform" means fecal and non-fecal coliform. - CORRECT
ANSWER ✔✔ - True
T/F: Pathogens are disease-causing microorganisms. - CORRECT ANSWER ✔✔ -
True
If a routine sample is positive, flush the positive sample point, check the chlorine
residual, then resample within 24 days of notification. - CORRECT ANSWER ✔✔ -
False (If a routine sample is total coliform-positive, the PWS should flush the
positive sample point, check the chlorine residual, then resample within *24 hrs*
of notification)
To prevent the formation of THMS in surface water, chlorine is combined with
_____ forming chloramine, combined chlorine residual. - CORRECT ANSWER ✔✔ -
Ammonia
If there is no chlorine ______ at a faucet, do not sample, flush longer. - CORRECT
ANSWER ✔✔ - residual
Pg. 2
, T/F: All repeat samples must be collected on successive days. - CORRECT ANSWER
✔✔ - False (Collect all repeat sample on the same day)
In the event of distribution pressure below ___ psi, _______ outages, repeated
bad samples or chlorine _____ below minimum, special precautions must be
instituted. - CORRECT ANSWER ✔✔ - 20/water/residual
Get the sample to the lab within ___________ or it will be rejected. - CORRECT
ANSWER ✔✔ - 30 hours (for BacT samples)
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
Pg. 3
