Page 1 of 38
09 June 2026
TCEQ CLASS D WATER OPERATOR LICENSE EXAM 2026 WITH
150 REAL EXAM QUESTIONS AND CORRECT ANSWERS/
TEXAS CLASS C WATER OPERATOR EXAM 2026/2027 LATEST
(NEW!!)
1. Plants ___ water vapor into the atmosphere through openings formed by specialized cells called
___.
A. Absorb / xylem
B. Release / lenticels
C. Transpire / stomata
D. Evaporate / guard cells
Correct Answer: C. Transpire / stomata
Rationale: Plants lose water vapor through transpiration, and the openings responsible are called
stomata.
2. The molecular weight of water is about ___ grams/mole.
A. 16
B. 18
C. 20
D. 22
Correct Answer: B. 18
Rationale: The molecular weight of water (H₂O) is approximately 18 grams per mole.
3. Pure water is a ___ conductor of electricity.
A. Excellent
B. Good
C. Moderate
D. Poor
Correct Answer: D. Poor
Rationale: Pure water contains very few ions and is therefore a poor conductor of electricity.
4. The water in oceans represents about ___% of the world's total water inventory.
A. 90%
B. 95%
, Page 2 of 38
09 June 2026
C. 97%
D. 99%
Correct Answer: C. 97%
Rationale: Approximately 97% of the Earth's water is found in the oceans.
5. 1.0 acre-foot is ___ gallons.
A. 300,000
B. 315,000
C. 325,851
D. 350,000
Correct Answer: C. 325,851
Rationale: One acre-foot of water equals approximately 325,851 gallons.
6. About ___% of the precipitation that falls on Texas in a year will return to the atmosphere by
evapotranspiration.
A. 75%
B. 82%
C. 89%
D. 95%
Correct Answer: C. 89%
Rationale: About 89% of Texas precipitation returns to the atmosphere through evapotranspiration.
7. Water goes from the surface, through the ground and into ___ by the process of ___.
A. Reservoirs / infiltration
B. Aquifers / percolation
C. Rivers / runoff
D. Lakes / absorption
Correct Answer: B. Aquifers / percolation
Rationale: Water percolates through the ground and enters aquifers.
8. Statewide, the total water usage is about ___ million acre-feet per year, most of which is for
___.
A. 10 / industry
B. 12 / municipal use
C. 16 / irrigation
D. 20 / recreation
, Page 3 of 38
09 June 2026
Correct Answer: C. 16 / irrigation
Rationale: Texas uses about 16 million acre-feet annually, with irrigation accounting for most of the
use.
9. On average, domestic sewage is about ___ residential and ___ commercial and institutional.
A. 50% / 50%
B. 2//3
C. 3//4
D. 4//5
Correct Answer: B. 2//3
Rationale: Domestic sewage is generally about two-thirds residential and one-third
commercial/institutional.
10. When the original sewers were built, the sewage was discharged to ___.
A. Treatment plants
B. Holding ponds
C. Rivers or streams
D. Groundwater wells
Correct Answer: C. Rivers or streams
Rationale: Early sewer systems commonly discharged untreated sewage directly into rivers and
streams.
11. The Imhoff tank was designed by Dr. Karl Imhoff in Germany in ___.
A. 1898
B. 1906
C. 1915
D. 1920
Correct Answer: B. 1906
Rationale: The Imhoff tank was designed by Dr. Karl Imhoff in Germany in 1906.
12. Which of the following is an example of a "point source"?
A. Agricultural runoff
B. Landfill runoff
C. POTW discharge and industrial discharge
D. Stormwater sheet flow
, Page 4 of 38
09 June 2026
Correct Answer: C. POTW discharge and industrial discharge
Rationale: Point sources are identifiable discharge points such as POTW and industrial discharges.
13. Which of the following is an example of a "non-point source"?
A. POTW outfall
B. Industrial discharge pipe
C. A landfill
D. Lift station discharge
Correct Answer: C. A landfill
Rationale: Non-point sources do not originate from a single identifiable discharge point.
14. The large sewer in Rome that was completed around 500 BC was called ___.
A. Aqua Appia
B. Via Roma
C. Cloaca Maxima
D. Roman Aqueduct
Correct Answer: C. Cloaca Maxima
Rationale: The Cloaca Maxima was one of the earliest major sewer systems in history.
15. The name for any matter in the water that renders it "undesirable" for human use is ___.
A. Contamination
B. Pollution
C. Sediment
D. Waste
Correct Answer: B. Pollution
Rationale: Pollution refers to matter that makes water undesirable for human use.
16. The name for any matter in the water that renders it "unfit" for human use is ___.
A. Pollution
B. Runoff
C. Contamination
D. Turbidity
Correct Answer: C. Contamination
Rationale: Contamination refers to matter that makes water unfit for human use.
09 June 2026
TCEQ CLASS D WATER OPERATOR LICENSE EXAM 2026 WITH
150 REAL EXAM QUESTIONS AND CORRECT ANSWERS/
TEXAS CLASS C WATER OPERATOR EXAM 2026/2027 LATEST
(NEW!!)
1. Plants ___ water vapor into the atmosphere through openings formed by specialized cells called
___.
A. Absorb / xylem
B. Release / lenticels
C. Transpire / stomata
D. Evaporate / guard cells
Correct Answer: C. Transpire / stomata
Rationale: Plants lose water vapor through transpiration, and the openings responsible are called
stomata.
2. The molecular weight of water is about ___ grams/mole.
A. 16
B. 18
C. 20
D. 22
Correct Answer: B. 18
Rationale: The molecular weight of water (H₂O) is approximately 18 grams per mole.
3. Pure water is a ___ conductor of electricity.
A. Excellent
B. Good
C. Moderate
D. Poor
Correct Answer: D. Poor
Rationale: Pure water contains very few ions and is therefore a poor conductor of electricity.
4. The water in oceans represents about ___% of the world's total water inventory.
A. 90%
B. 95%
, Page 2 of 38
09 June 2026
C. 97%
D. 99%
Correct Answer: C. 97%
Rationale: Approximately 97% of the Earth's water is found in the oceans.
5. 1.0 acre-foot is ___ gallons.
A. 300,000
B. 315,000
C. 325,851
D. 350,000
Correct Answer: C. 325,851
Rationale: One acre-foot of water equals approximately 325,851 gallons.
6. About ___% of the precipitation that falls on Texas in a year will return to the atmosphere by
evapotranspiration.
A. 75%
B. 82%
C. 89%
D. 95%
Correct Answer: C. 89%
Rationale: About 89% of Texas precipitation returns to the atmosphere through evapotranspiration.
7. Water goes from the surface, through the ground and into ___ by the process of ___.
A. Reservoirs / infiltration
B. Aquifers / percolation
C. Rivers / runoff
D. Lakes / absorption
Correct Answer: B. Aquifers / percolation
Rationale: Water percolates through the ground and enters aquifers.
8. Statewide, the total water usage is about ___ million acre-feet per year, most of which is for
___.
A. 10 / industry
B. 12 / municipal use
C. 16 / irrigation
D. 20 / recreation
, Page 3 of 38
09 June 2026
Correct Answer: C. 16 / irrigation
Rationale: Texas uses about 16 million acre-feet annually, with irrigation accounting for most of the
use.
9. On average, domestic sewage is about ___ residential and ___ commercial and institutional.
A. 50% / 50%
B. 2//3
C. 3//4
D. 4//5
Correct Answer: B. 2//3
Rationale: Domestic sewage is generally about two-thirds residential and one-third
commercial/institutional.
10. When the original sewers were built, the sewage was discharged to ___.
A. Treatment plants
B. Holding ponds
C. Rivers or streams
D. Groundwater wells
Correct Answer: C. Rivers or streams
Rationale: Early sewer systems commonly discharged untreated sewage directly into rivers and
streams.
11. The Imhoff tank was designed by Dr. Karl Imhoff in Germany in ___.
A. 1898
B. 1906
C. 1915
D. 1920
Correct Answer: B. 1906
Rationale: The Imhoff tank was designed by Dr. Karl Imhoff in Germany in 1906.
12. Which of the following is an example of a "point source"?
A. Agricultural runoff
B. Landfill runoff
C. POTW discharge and industrial discharge
D. Stormwater sheet flow
, Page 4 of 38
09 June 2026
Correct Answer: C. POTW discharge and industrial discharge
Rationale: Point sources are identifiable discharge points such as POTW and industrial discharges.
13. Which of the following is an example of a "non-point source"?
A. POTW outfall
B. Industrial discharge pipe
C. A landfill
D. Lift station discharge
Correct Answer: C. A landfill
Rationale: Non-point sources do not originate from a single identifiable discharge point.
14. The large sewer in Rome that was completed around 500 BC was called ___.
A. Aqua Appia
B. Via Roma
C. Cloaca Maxima
D. Roman Aqueduct
Correct Answer: C. Cloaca Maxima
Rationale: The Cloaca Maxima was one of the earliest major sewer systems in history.
15. The name for any matter in the water that renders it "undesirable" for human use is ___.
A. Contamination
B. Pollution
C. Sediment
D. Waste
Correct Answer: B. Pollution
Rationale: Pollution refers to matter that makes water undesirable for human use.
16. The name for any matter in the water that renders it "unfit" for human use is ___.
A. Pollution
B. Runoff
C. Contamination
D. Turbidity
Correct Answer: C. Contamination
Rationale: Contamination refers to matter that makes water unfit for human use.
