TCEQ Class D Water Operator License
Exam 2026/2027 | Texas Water
Treatment Study Guide
Description: This comprehensive 200-question MCQ study guide covers all essential
domains for the TCEQ Class D Water Operator License Exam. Topics include water
sources and hydrologic cycle, public water system classifications, regulations (SDWA,
TCEQ, 30 TAC 290), treatment processes (coagulation, sedimentation, filtration,
disinfection), distribution systems, storage, pumps, safety procedures, and operator
responsibilities. Each question includes the correct answer marked with ✅ for efficient
revision.
Keywords: TCEQ, Class D Water Operator, Texas water license, water treatment,
distribution system, SDWA, disinfection, chlorination, cross-connection, backflow
prevention, storage tanks, pumps, hydrologic cycle, potable water, MCL, bacteriological
sampling, water math, safety procedures
Section 1: Water Sources & Hydrologic Cycle (Q1-Q20)
Q1. What percentage of the Earth's surface is covered by water?
A. 50%
B. 61%
C. 71% ✅
D. 81%
Q2. Only about what percentage of all fresh water on Earth can be easily accessed
for use?
,A. 3%
B. 10%
C. 1% ✅
D. 25%
Q3. What is the natural exchange of water between the earth and atmosphere
called?
A. Water treatment cycle
B. Hydrologic cycle ✅
C. Distribution cycle
D. Filtration cycle
Q4. Which of the following is NOT a process in the hydrologic cycle?
A. Evaporation
B. Condensation
C. Chlorination ✅
D. Precipitation
Q5. Water that seeps into the ground and replenishes underground aquifers is
called:
A. Surface runoff
B. Transpiration
C. Groundwater recharge ✅
D. Condensation
Q6. What is a water-bearing formation of rock or sand that yields useful quantities
of water?
A. Reservoir
B. Aquifer ✅
,C. Watershed
D. Basin
Q7. What is the primary source of groundwater?
A. Rivers and lakes
B. Precipitation infiltrating the soil ✅
C. Ocean water
D. Treated wastewater
Q8. Surface water comes from which of the following sources?
A. Aquifers
B. Rivers, lakes, and reservoirs ✅
C. Deep wells
D. Springs only
Q9. What is drought?
A. A period of excessive rainfall
B. An extended period when a region receives a deficiency in its water supply ✅
C. Seasonal temperature changes
D. Flooding events
Q10. In Texas, approximately what percentage of all water is used for commercial,
industrial, or agricultural purposes?
A. 35%
B. 45%
C. 57%
D. 75% ✅
Q11. In Texas, agricultural water demand accounts for approximately what
percentage of total water used?
, A. 35%
B. 45%
C. 57% ✅
D. 75%
Q12. What Texas water law allows a landowner to pump as much groundwater as
desired, even if it drains from beneath neighboring land?
A. Riparian Doctrine
B. Rule of Capture ✅
C. Prior Appropriation
D. Water Rights Act
Q13. How many major river basins are located in Texas?
A. 15
B. 23 ✅
C. 32
D. 40
Q14. What is the volume of one acre-foot of water in gallons?
A. 100,000 gallons
B. 225,000 gallons
C. 325,000 gallons ✅
D. 500,000 gallons
Q15. Most groundwater is relatively free of suspended matter, but what can be a
major problem in surface water?
A. Turbidity ✅
B. Hardness
C. Alkalinity
D. Salinity
Exam 2026/2027 | Texas Water
Treatment Study Guide
Description: This comprehensive 200-question MCQ study guide covers all essential
domains for the TCEQ Class D Water Operator License Exam. Topics include water
sources and hydrologic cycle, public water system classifications, regulations (SDWA,
TCEQ, 30 TAC 290), treatment processes (coagulation, sedimentation, filtration,
disinfection), distribution systems, storage, pumps, safety procedures, and operator
responsibilities. Each question includes the correct answer marked with ✅ for efficient
revision.
Keywords: TCEQ, Class D Water Operator, Texas water license, water treatment,
distribution system, SDWA, disinfection, chlorination, cross-connection, backflow
prevention, storage tanks, pumps, hydrologic cycle, potable water, MCL, bacteriological
sampling, water math, safety procedures
Section 1: Water Sources & Hydrologic Cycle (Q1-Q20)
Q1. What percentage of the Earth's surface is covered by water?
A. 50%
B. 61%
C. 71% ✅
D. 81%
Q2. Only about what percentage of all fresh water on Earth can be easily accessed
for use?
,A. 3%
B. 10%
C. 1% ✅
D. 25%
Q3. What is the natural exchange of water between the earth and atmosphere
called?
A. Water treatment cycle
B. Hydrologic cycle ✅
C. Distribution cycle
D. Filtration cycle
Q4. Which of the following is NOT a process in the hydrologic cycle?
A. Evaporation
B. Condensation
C. Chlorination ✅
D. Precipitation
Q5. Water that seeps into the ground and replenishes underground aquifers is
called:
A. Surface runoff
B. Transpiration
C. Groundwater recharge ✅
D. Condensation
Q6. What is a water-bearing formation of rock or sand that yields useful quantities
of water?
A. Reservoir
B. Aquifer ✅
,C. Watershed
D. Basin
Q7. What is the primary source of groundwater?
A. Rivers and lakes
B. Precipitation infiltrating the soil ✅
C. Ocean water
D. Treated wastewater
Q8. Surface water comes from which of the following sources?
A. Aquifers
B. Rivers, lakes, and reservoirs ✅
C. Deep wells
D. Springs only
Q9. What is drought?
A. A period of excessive rainfall
B. An extended period when a region receives a deficiency in its water supply ✅
C. Seasonal temperature changes
D. Flooding events
Q10. In Texas, approximately what percentage of all water is used for commercial,
industrial, or agricultural purposes?
A. 35%
B. 45%
C. 57%
D. 75% ✅
Q11. In Texas, agricultural water demand accounts for approximately what
percentage of total water used?
, A. 35%
B. 45%
C. 57% ✅
D. 75%
Q12. What Texas water law allows a landowner to pump as much groundwater as
desired, even if it drains from beneath neighboring land?
A. Riparian Doctrine
B. Rule of Capture ✅
C. Prior Appropriation
D. Water Rights Act
Q13. How many major river basins are located in Texas?
A. 15
B. 23 ✅
C. 32
D. 40
Q14. What is the volume of one acre-foot of water in gallons?
A. 100,000 gallons
B. 225,000 gallons
C. 325,000 gallons ✅
D. 500,000 gallons
Q15. Most groundwater is relatively free of suspended matter, but what can be a
major problem in surface water?
A. Turbidity ✅
B. Hardness
C. Alkalinity
D. Salinity
