Page 1 of 34
Friday, May 8, 2026
TCEQ CLASS C WATER LICENSE EXAM |VERIFIED
150Qs&As|NEW UPDATE|TCEQ EXAM PREP
2026|A+GRADE
Question 1
Which state agency is responsible for enforcing the Safe Drinking Water Act in Texas?
A. Texas Department of Health
B. Texas Water Development Board
C. Texas Commission on Environmental Quality
D. Environmental Protection Agency
Correct Answer: C. Texas Commission on Environmental Quality
Rationale: The Texas Commission on Environmental Quality (TCEQ) is the primary state agency
responsible for regulating public water systems and enforcing drinking water standards in Texas.
Question 2
Which minerals are primarily responsible for water hardness?
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and manganese
D. Sulfur and zinc
Correct Answer: B. Calcium and magnesium
Rationale: Water hardness is caused mainly by dissolved calcium and magnesium ions commonly found
in groundwater.
Question 3
A public water system must at all times provide:
A. Unlimited water supply
B. Chlorinated wastewater
C. Adequate quantity, pressure, and disinfection
D. Fluoridated groundwater only
Correct Answer: C. Adequate quantity, pressure, and disinfection
, Page 2 of 34
Friday, May 8, 2026
Rationale: Public water systems are required to maintain safe drinking water with adequate pressure,
sufficient quantity, and proper disinfection.
Question 4
A groundwater source is commonly obtained from a(n):
A. River
B. Reservoir
C. Ocean
D. Aquifer
Correct Answer: D. Aquifer
Rationale: Groundwater is stored underground in water-bearing formations known as aquifers.
Question 5
The presence of fecal coliform organisms in water indicates that:
A. The water contains excess minerals
B. Harmful contamination may be present
C. The water is over-chlorinated
D. The pH is too low
Correct Answer: B. Harmful contamination may be present
Rationale: Fecal coliform bacteria indicate possible contamination from human or animal waste and the
potential presence of pathogens.
Question 6
Which disease may result from inadequately disinfected drinking water?
A. Diabetes
B. Asthma
C. Dysentery
D. Arthritis
Correct Answer: C. Dysentery
Rationale: Dysentery is a waterborne disease caused by pathogens that may survive in improperly
disinfected water.
Question 7
, Page 3 of 34
Friday, May 8, 2026
A common disinfectant used in small water systems is:
A. Alum
B. Potassium nitrate
C. Ferric sulfate
D. Calcium hypochlorite
Correct Answer: D. Calcium hypochlorite
Rationale: Calcium hypochlorite (HTH) is widely used in small systems because it is stable and easy to
handle.
Question 8
A physical connection between a potable water supply and a private well is called a:
A. Hydraulic seal
B. Vacuum break
C. Cross connection
D. Pressure zone
Correct Answer: C. Cross connection
Rationale: Cross connections can allow contaminants to enter the potable water supply and are a major
public health concern.
Question 9
The amount of chlorine consumed by reactions with iron, organics, and bacteria is called:
A. Residual
B. Dosage
C. Demand
D. Oxidation
Correct Answer: C. Demand
Rationale: Chlorine demand refers to the amount of chlorine used up before a residual is established.
Question 10
Which characteristic describes chlorine gas?
A. Colorless and lighter than air
B. Blue with no odor
C. Odorless and noncorrosive
D. Greenish-yellow and heavier than air
, Page 4 of 34
Friday, May 8, 2026
Correct Answer: D. Greenish-yellow and heavier than air
Rationale: Chlorine gas is toxic, corrosive, heavier than air, and has a strong penetrating odor.
Question 11
Which component is part of a hypochlorinator system?
A. Sedimentation basin
B. Solution feed pump
C. Venturi meter
D. Clarifier rake
Correct Answer: B. Solution feed pump
Rationale: A hypochlorinator uses a solution feed pump to inject chlorine solution into the water.
Question 12
According to state requirements, public water supply wells should include screened vents and:
A. A grease trap
B. A chlorine scrubber
C. A flow measuring device
D. A sludge collector
Correct Answer: C. A flow measuring device
Rationale: Flow measuring devices are required to monitor well production and system performance.
Question 13
Drawdown in a well is determined by the difference between:
A. Pump size and pipe size
B. Static and pumping water levels
C. Chlorine dosage and residual
D. Pressure and velocity
Correct Answer: B. Static and pumping water levels
Rationale: Drawdown measures how far the water level drops while the well is pumping.
Question 14
The pH of water indicates whether the water is:
Friday, May 8, 2026
TCEQ CLASS C WATER LICENSE EXAM |VERIFIED
150Qs&As|NEW UPDATE|TCEQ EXAM PREP
2026|A+GRADE
Question 1
Which state agency is responsible for enforcing the Safe Drinking Water Act in Texas?
A. Texas Department of Health
B. Texas Water Development Board
C. Texas Commission on Environmental Quality
D. Environmental Protection Agency
Correct Answer: C. Texas Commission on Environmental Quality
Rationale: The Texas Commission on Environmental Quality (TCEQ) is the primary state agency
responsible for regulating public water systems and enforcing drinking water standards in Texas.
Question 2
Which minerals are primarily responsible for water hardness?
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and manganese
D. Sulfur and zinc
Correct Answer: B. Calcium and magnesium
Rationale: Water hardness is caused mainly by dissolved calcium and magnesium ions commonly found
in groundwater.
Question 3
A public water system must at all times provide:
A. Unlimited water supply
B. Chlorinated wastewater
C. Adequate quantity, pressure, and disinfection
D. Fluoridated groundwater only
Correct Answer: C. Adequate quantity, pressure, and disinfection
, Page 2 of 34
Friday, May 8, 2026
Rationale: Public water systems are required to maintain safe drinking water with adequate pressure,
sufficient quantity, and proper disinfection.
Question 4
A groundwater source is commonly obtained from a(n):
A. River
B. Reservoir
C. Ocean
D. Aquifer
Correct Answer: D. Aquifer
Rationale: Groundwater is stored underground in water-bearing formations known as aquifers.
Question 5
The presence of fecal coliform organisms in water indicates that:
A. The water contains excess minerals
B. Harmful contamination may be present
C. The water is over-chlorinated
D. The pH is too low
Correct Answer: B. Harmful contamination may be present
Rationale: Fecal coliform bacteria indicate possible contamination from human or animal waste and the
potential presence of pathogens.
Question 6
Which disease may result from inadequately disinfected drinking water?
A. Diabetes
B. Asthma
C. Dysentery
D. Arthritis
Correct Answer: C. Dysentery
Rationale: Dysentery is a waterborne disease caused by pathogens that may survive in improperly
disinfected water.
Question 7
, Page 3 of 34
Friday, May 8, 2026
A common disinfectant used in small water systems is:
A. Alum
B. Potassium nitrate
C. Ferric sulfate
D. Calcium hypochlorite
Correct Answer: D. Calcium hypochlorite
Rationale: Calcium hypochlorite (HTH) is widely used in small systems because it is stable and easy to
handle.
Question 8
A physical connection between a potable water supply and a private well is called a:
A. Hydraulic seal
B. Vacuum break
C. Cross connection
D. Pressure zone
Correct Answer: C. Cross connection
Rationale: Cross connections can allow contaminants to enter the potable water supply and are a major
public health concern.
Question 9
The amount of chlorine consumed by reactions with iron, organics, and bacteria is called:
A. Residual
B. Dosage
C. Demand
D. Oxidation
Correct Answer: C. Demand
Rationale: Chlorine demand refers to the amount of chlorine used up before a residual is established.
Question 10
Which characteristic describes chlorine gas?
A. Colorless and lighter than air
B. Blue with no odor
C. Odorless and noncorrosive
D. Greenish-yellow and heavier than air
, Page 4 of 34
Friday, May 8, 2026
Correct Answer: D. Greenish-yellow and heavier than air
Rationale: Chlorine gas is toxic, corrosive, heavier than air, and has a strong penetrating odor.
Question 11
Which component is part of a hypochlorinator system?
A. Sedimentation basin
B. Solution feed pump
C. Venturi meter
D. Clarifier rake
Correct Answer: B. Solution feed pump
Rationale: A hypochlorinator uses a solution feed pump to inject chlorine solution into the water.
Question 12
According to state requirements, public water supply wells should include screened vents and:
A. A grease trap
B. A chlorine scrubber
C. A flow measuring device
D. A sludge collector
Correct Answer: C. A flow measuring device
Rationale: Flow measuring devices are required to monitor well production and system performance.
Question 13
Drawdown in a well is determined by the difference between:
A. Pump size and pipe size
B. Static and pumping water levels
C. Chlorine dosage and residual
D. Pressure and velocity
Correct Answer: B. Static and pumping water levels
Rationale: Drawdown measures how far the water level drops while the well is pumping.
Question 14
The pH of water indicates whether the water is:
