TCEQ Class C Water License Exam | Complete Practice
Exam with Verified Correct Answers and Detailed
Rationales(100% Correct Solutions) | Latest Update
2026/2027 – Already Graded A+
Question 1
The most important federal law that impacts the water utility industry is:
A. The Resource Conservation and Recovery Act
B. The Safe Drinking Water Act of 1974
C. The Clean Water Act of 1972
D. The Clean Air Act of 1970
Answer: B
Rationale: The Safe Drinking Water Act (SDWA) of 1974 is the most important federal
law impacting the water utility industry as it establishes standards for drinking water
quality, regulates public water systems, and sets maximum contaminant levels for various
pollutants. The Clean Water Act (C) regulates surface water quality, not drinking water
specifically.
Question 2
If a water lubricated vertical turbine pump is started with dry bearings:
A. The motor will overheat immediately
B. The bearings will be damaged
C. The pump will produce no water
D. The pressure will drop to zero
Answer: B
Rationale: Water lubricated vertical turbine pumps rely on water to lubricate the
bearings during operation. Starting with dry bearings causes metal-on-metal contact,
leading to rapid bearing damage and premature pump failure.
Question 3
A storage vessel that is the same diameter from the ground to the top and is more than 20
feet but less than 80 feet tall is called a:
A. Shaft
B. Drawdown
C. Stand pipe
D. Piston
Answer: C
Rationale: A standpipe is a cylindrical storage tank with a uniform diameter from ground
pg. 1
,level to the top, typically ranging from 20 to 80 feet in height. It provides water storage
and maintains system pressure through elevation.
Question 4
A disease that may be spread by inadequately disinfected water:
A. Malaria
B. Dysentery
C. Influenza
D. Asthma
Answer: B
Rationale: Dysentery is a waterborne disease caused by bacteria or parasites such as
Shigella or Entamoeba histolytica that can be transmitted through inadequately
disinfected water. Malaria (A) is mosquito-borne, influenza (C) is airborne, and asthma
(D) is not a communicable disease.
Question 5
At the base of an elevated storage tank a pressure gauge reads 72 psi. How far above the
gauge is the water surface?
A. 100 feet
B. 166 feet
C. 200 feet
D. 132 feet
Answer: B
Rationale: Using the conversion factor of 1 psi = 2.31 feet of water, 72 psi × 2.31 ft/psi =
166.32 feet. This principle is essential for calculating water levels from pressure readings
in elevated storage tanks.
Question 6
The maximum safe withdrawal rate of Chlorine for a 150 pound cylinder is:
A. 40 lbs in 24 hours
B. 60 lbs in 24 hours
C. 20 lbs in 24 hours
D. 10 lbs in 24 hours
Answer: A
Rationale: The maximum safe withdrawal rate for a 150 lb chlorine cylinder is 40 lbs per
24 hours. Exceeding this rate can cause the cylinder to ice up and reduce chlorine flow,
potentially leading to safety hazards.
Question 7
Most common type of filter in a surface plant is ______ and is designed to treat and flow
pg. 2
,at ______:
A. Cartridge and designed to flow 5 gpm/ft2
B. Rapid sand and designed to flow 2 gpm/ft2
C. Diatomaceous earth and designed to flow 1 gpm/ft2
D. Slow sand and designed to flow 0.1 gpm/ft2
Answer: B
Rationale: Rapid sand filters are the most common type used in surface water treatment
plants, designed to operate at approximately 2 gallons per minute per square foot
(gpm/ft²). This high filtration rate makes them efficient for treating large volumes of
water.
Question 8
Check valves on the discharge side of a pump are used to:
A. Prevent water from flowing back through the pump when the pump is off
B. Determine Water levels in the well
C. Elevated storage tanks
D. Detect problems with the pump, well screen, and/or water level
Answer: A
Rationale: Check valves are installed on the discharge side of pumps to prevent
backflow when the pump is not operating. This prevents water from flowing backward
through the pump, which could cause the pump to spin backwards and potentially
damage the equipment.
Question 9
Potable water is maintained at:
A. Adequate pressure, pathogen free, and contains a chlorine residual
B. Low turbidity and constant temperature
C. Excessive pressure and high flow rates
D. Continuous chlorination and high turbidity
Answer: A
Rationale: Potable (drinking) water must be maintained at adequate pressure to ensure
distribution, be pathogen-free through proper disinfection, and contain a chlorine residual
to maintain protection throughout the distribution system.
Question 10
pH of water indicates:
A. If it's acidic or basic
B. If it is safe to drink
C. If it contains dissolved solids
D. If it's hard or soft
pg. 3
, Answer: A
Rationale: pH indicates whether water is acidic (below 7.0) or basic (above 7.0). A pH
of 7.0 is neutral. pH does not directly indicate safety (B), dissolved solids (C), or
hardness (D).
Question 11
The primary reason for main line failures in the distribution system is:
A. Internal and external corrosion, improper backfill, and lack of proper bedding
B. Water supply contamination and harmful bacteria
C. Screened vents and approved locking roof hatch issues
D. Cross connections and backflow
Answer: A
Rationale: Main line failures are primarily caused by internal and external corrosion,
improper backfill, and lack of proper bedding. These issues compromise pipe integrity,
leading to leaks and breaks in the distribution system.
Question 12
The top of a pipe in a trench must be at least ______ inches from the top of the ground:
A. 4
B. 24
C. 35
D. 30
Answer: B
Rationale: The top of a pipe must be at least 24 inches below the ground surface to
provide adequate cover and protection from freezing, surface loads, and excavation
damage.
Question 13
In small systems liquid bleach is an approved method of disinfection, provided the
product used meets basic industry standards. What is the current standard bleach must
meet in order to be approved for disinfection in a public water system?
A. Must be labeled as food grade by the FDA
B. Must contain at least 10% sodium hypochlorite
C. Must conform to the National Sanitation Foundation (NSF) Standard 60
D. Must be purchased from a certified chemical supplier only
Answer: C
Rationale: Bleach used in public water systems must conform to NSF Standard 60,
which ensures that the product meets health effects standards for drinking water treatment
chemicals. This is the current standard for approved disinfectants.
pg. 4
Exam with Verified Correct Answers and Detailed
Rationales(100% Correct Solutions) | Latest Update
2026/2027 – Already Graded A+
Question 1
The most important federal law that impacts the water utility industry is:
A. The Resource Conservation and Recovery Act
B. The Safe Drinking Water Act of 1974
C. The Clean Water Act of 1972
D. The Clean Air Act of 1970
Answer: B
Rationale: The Safe Drinking Water Act (SDWA) of 1974 is the most important federal
law impacting the water utility industry as it establishes standards for drinking water
quality, regulates public water systems, and sets maximum contaminant levels for various
pollutants. The Clean Water Act (C) regulates surface water quality, not drinking water
specifically.
Question 2
If a water lubricated vertical turbine pump is started with dry bearings:
A. The motor will overheat immediately
B. The bearings will be damaged
C. The pump will produce no water
D. The pressure will drop to zero
Answer: B
Rationale: Water lubricated vertical turbine pumps rely on water to lubricate the
bearings during operation. Starting with dry bearings causes metal-on-metal contact,
leading to rapid bearing damage and premature pump failure.
Question 3
A storage vessel that is the same diameter from the ground to the top and is more than 20
feet but less than 80 feet tall is called a:
A. Shaft
B. Drawdown
C. Stand pipe
D. Piston
Answer: C
Rationale: A standpipe is a cylindrical storage tank with a uniform diameter from ground
pg. 1
,level to the top, typically ranging from 20 to 80 feet in height. It provides water storage
and maintains system pressure through elevation.
Question 4
A disease that may be spread by inadequately disinfected water:
A. Malaria
B. Dysentery
C. Influenza
D. Asthma
Answer: B
Rationale: Dysentery is a waterborne disease caused by bacteria or parasites such as
Shigella or Entamoeba histolytica that can be transmitted through inadequately
disinfected water. Malaria (A) is mosquito-borne, influenza (C) is airborne, and asthma
(D) is not a communicable disease.
Question 5
At the base of an elevated storage tank a pressure gauge reads 72 psi. How far above the
gauge is the water surface?
A. 100 feet
B. 166 feet
C. 200 feet
D. 132 feet
Answer: B
Rationale: Using the conversion factor of 1 psi = 2.31 feet of water, 72 psi × 2.31 ft/psi =
166.32 feet. This principle is essential for calculating water levels from pressure readings
in elevated storage tanks.
Question 6
The maximum safe withdrawal rate of Chlorine for a 150 pound cylinder is:
A. 40 lbs in 24 hours
B. 60 lbs in 24 hours
C. 20 lbs in 24 hours
D. 10 lbs in 24 hours
Answer: A
Rationale: The maximum safe withdrawal rate for a 150 lb chlorine cylinder is 40 lbs per
24 hours. Exceeding this rate can cause the cylinder to ice up and reduce chlorine flow,
potentially leading to safety hazards.
Question 7
Most common type of filter in a surface plant is ______ and is designed to treat and flow
pg. 2
,at ______:
A. Cartridge and designed to flow 5 gpm/ft2
B. Rapid sand and designed to flow 2 gpm/ft2
C. Diatomaceous earth and designed to flow 1 gpm/ft2
D. Slow sand and designed to flow 0.1 gpm/ft2
Answer: B
Rationale: Rapid sand filters are the most common type used in surface water treatment
plants, designed to operate at approximately 2 gallons per minute per square foot
(gpm/ft²). This high filtration rate makes them efficient for treating large volumes of
water.
Question 8
Check valves on the discharge side of a pump are used to:
A. Prevent water from flowing back through the pump when the pump is off
B. Determine Water levels in the well
C. Elevated storage tanks
D. Detect problems with the pump, well screen, and/or water level
Answer: A
Rationale: Check valves are installed on the discharge side of pumps to prevent
backflow when the pump is not operating. This prevents water from flowing backward
through the pump, which could cause the pump to spin backwards and potentially
damage the equipment.
Question 9
Potable water is maintained at:
A. Adequate pressure, pathogen free, and contains a chlorine residual
B. Low turbidity and constant temperature
C. Excessive pressure and high flow rates
D. Continuous chlorination and high turbidity
Answer: A
Rationale: Potable (drinking) water must be maintained at adequate pressure to ensure
distribution, be pathogen-free through proper disinfection, and contain a chlorine residual
to maintain protection throughout the distribution system.
Question 10
pH of water indicates:
A. If it's acidic or basic
B. If it is safe to drink
C. If it contains dissolved solids
D. If it's hard or soft
pg. 3
, Answer: A
Rationale: pH indicates whether water is acidic (below 7.0) or basic (above 7.0). A pH
of 7.0 is neutral. pH does not directly indicate safety (B), dissolved solids (C), or
hardness (D).
Question 11
The primary reason for main line failures in the distribution system is:
A. Internal and external corrosion, improper backfill, and lack of proper bedding
B. Water supply contamination and harmful bacteria
C. Screened vents and approved locking roof hatch issues
D. Cross connections and backflow
Answer: A
Rationale: Main line failures are primarily caused by internal and external corrosion,
improper backfill, and lack of proper bedding. These issues compromise pipe integrity,
leading to leaks and breaks in the distribution system.
Question 12
The top of a pipe in a trench must be at least ______ inches from the top of the ground:
A. 4
B. 24
C. 35
D. 30
Answer: B
Rationale: The top of a pipe must be at least 24 inches below the ground surface to
provide adequate cover and protection from freezing, surface loads, and excavation
damage.
Question 13
In small systems liquid bleach is an approved method of disinfection, provided the
product used meets basic industry standards. What is the current standard bleach must
meet in order to be approved for disinfection in a public water system?
A. Must be labeled as food grade by the FDA
B. Must contain at least 10% sodium hypochlorite
C. Must conform to the National Sanitation Foundation (NSF) Standard 60
D. Must be purchased from a certified chemical supplier only
Answer: C
Rationale: Bleach used in public water systems must conform to NSF Standard 60,
which ensures that the product meets health effects standards for drinking water treatment
chemicals. This is the current standard for approved disinfectants.
pg. 4
