TCEQ Class C Water License Exam | Complete
Study Guides with Actual Exam Questions,
Verified Correct Answers and Detailed Rationales
| Latest Update 2026/2027
Question 1
When treating surface water, the process of coagulation will be most affected by the:
A. Pressure, hardness, acidity, and oxygen levels
B. pH, alkalinity, temperature, and chemical dosage
C. Density, viscosity, color, and mineral content
D. Temperature, turbidity, salinity, and flow rate
Answer: B
Rationale: Coagulation is most affected by pH, alkalinity, temperature, and chemical dosage.
These factors determine the effectiveness of the coagulant in destabilizing particles.
Question 2
When an air gap is not practical, other acceptable backflow prevention devices are acceptable in
certain circumstances. All of the following are acceptable except:
A. Atmospheric vacuum breaker
B. Pressure vacuum breaker
C. Testable double check valve assemblies
D. Reduced pressure zoning devices
Answer: All are acceptable
Rationale: All of these are acceptable backflow prevention devices depending on the application
and degree of hazard.
Question 3
Water that is considered neutral is expressed on the pH scale at:
A. 6.0
B. 5.5
C. 8.0
D. 7.0
Answer: D
pg. 1
,Rationale: A pH of 7.0 is neutral. Values below 7.0 are acidic, and values above 7.0 are basic
(alkaline).
Question 4
The results of bacteriological analysis shall be kept on file and available for ______ years:
A. 7
B. 4
C. 5
D. 24
Answer: C
Rationale: Bacteriological analysis records must be kept on file for 5 years per TCEQ
requirements.
Question 5
One horsepower (1 hp) is equal to ______ foot-pounds of force per minute:
A. 30,000 foot-pounds
B. 40,000 foot-pounds
C. 33,000 foot-pounds
D. 25,000 foot-pounds
Answer: C
Rationale: One horsepower equals 33,000 foot-pounds of work per minute.
Question 6
Excess fluoride in water may be removed by:
A. Potassium permanganate
B. Free available chlorine
C. Activated alumina
D. Calcium chloride
Answer: C
Rationale: Activated alumina is commonly used to remove excess fluoride from drinking water
through adsorption.
Question 7
The top of a pipe in a trench must be at least ______ inches from the top of the ground:
A. 24
B. 35
pg. 2
,C. 5
D. 500
Answer: A
Rationale: The top of a pipe must be at least 24 inches below the ground surface to protect it
from freezing and physical damage.
Question 8
Using a ton cylinder, the maximum withdrawal rate should not exceed:
A. 600 pounds
B. 500 pounds
C. 400 pounds
D. 300 pounds
Answer: B
Rationale: The maximum withdrawal rate from a ton cylinder is 500 pounds per day to prevent
freezing of the chlorine and ensure safe operation.
Question 9
Trihalomethanes are formed by the reaction of ______ with organic chemicals:
A. Free available chlorine
B. Ultraviolet radiation
C. Chlorine dioxide
D. Ozone
Answer: A
Rationale: Trihalomethanes (THMs) are disinfection byproducts formed when free available
chlorine reacts with natural organic matter in water.
Question 10
At the base of an elevated storage tank, a pressure gauge reads 72 psi. How far above the gauge
is the water surface?
A. 166 feet
B. 145 feet
C. 200 feet
D. 120 feet
Answer: A
Rationale: 1 psi = 2.31 feet of water. 72 psi × 2.31 ft/psi = 166.32 feet.
pg. 3
, Question 11
The most commonly used pump in the distribution system is:
A. Centrifugal
B. Frictional
C. Reciprocating
D. Ekman spiral
Answer: A
Rationale: Centrifugal pumps are the most common type used in water distribution systems due
to their efficiency and simplicity.
Question 12
When designing systems, engineers use a rule of thumb of ______ gallons per person per day
when more accurate data isn't available:
A. 150
B. 100
C. 130
D. 80
Answer: B
Rationale: The standard design flow is 100 gallons per person per day for residential use.
Question 13
A certified operator doing routine daily checks discovers a cut lock on the entry gate and a cut
lock on the roof hatch with suspicious containers. What should the operator do?
A. Immediately notify TCEQ Regional office; they will notify law enforcement and investigate
B. Pull the electrical disconnect on the pumps and close valves isolating the tank until analyzed
C. Enter the tank to investigate
D. Ignore it and continue routine checks
Answer: A
Rationale: The operator must immediately notify the TCEQ Regional Office, who will notify
law enforcement and investigate to determine if there is a danger or threat to public health and
safety.
Question 14
Waterlines should be installed no closer than ______ feet to any sewer lines or other possible
contaminant lines:
A. 500
B. 9
pg. 4
Study Guides with Actual Exam Questions,
Verified Correct Answers and Detailed Rationales
| Latest Update 2026/2027
Question 1
When treating surface water, the process of coagulation will be most affected by the:
A. Pressure, hardness, acidity, and oxygen levels
B. pH, alkalinity, temperature, and chemical dosage
C. Density, viscosity, color, and mineral content
D. Temperature, turbidity, salinity, and flow rate
Answer: B
Rationale: Coagulation is most affected by pH, alkalinity, temperature, and chemical dosage.
These factors determine the effectiveness of the coagulant in destabilizing particles.
Question 2
When an air gap is not practical, other acceptable backflow prevention devices are acceptable in
certain circumstances. All of the following are acceptable except:
A. Atmospheric vacuum breaker
B. Pressure vacuum breaker
C. Testable double check valve assemblies
D. Reduced pressure zoning devices
Answer: All are acceptable
Rationale: All of these are acceptable backflow prevention devices depending on the application
and degree of hazard.
Question 3
Water that is considered neutral is expressed on the pH scale at:
A. 6.0
B. 5.5
C. 8.0
D. 7.0
Answer: D
pg. 1
,Rationale: A pH of 7.0 is neutral. Values below 7.0 are acidic, and values above 7.0 are basic
(alkaline).
Question 4
The results of bacteriological analysis shall be kept on file and available for ______ years:
A. 7
B. 4
C. 5
D. 24
Answer: C
Rationale: Bacteriological analysis records must be kept on file for 5 years per TCEQ
requirements.
Question 5
One horsepower (1 hp) is equal to ______ foot-pounds of force per minute:
A. 30,000 foot-pounds
B. 40,000 foot-pounds
C. 33,000 foot-pounds
D. 25,000 foot-pounds
Answer: C
Rationale: One horsepower equals 33,000 foot-pounds of work per minute.
Question 6
Excess fluoride in water may be removed by:
A. Potassium permanganate
B. Free available chlorine
C. Activated alumina
D. Calcium chloride
Answer: C
Rationale: Activated alumina is commonly used to remove excess fluoride from drinking water
through adsorption.
Question 7
The top of a pipe in a trench must be at least ______ inches from the top of the ground:
A. 24
B. 35
pg. 2
,C. 5
D. 500
Answer: A
Rationale: The top of a pipe must be at least 24 inches below the ground surface to protect it
from freezing and physical damage.
Question 8
Using a ton cylinder, the maximum withdrawal rate should not exceed:
A. 600 pounds
B. 500 pounds
C. 400 pounds
D. 300 pounds
Answer: B
Rationale: The maximum withdrawal rate from a ton cylinder is 500 pounds per day to prevent
freezing of the chlorine and ensure safe operation.
Question 9
Trihalomethanes are formed by the reaction of ______ with organic chemicals:
A. Free available chlorine
B. Ultraviolet radiation
C. Chlorine dioxide
D. Ozone
Answer: A
Rationale: Trihalomethanes (THMs) are disinfection byproducts formed when free available
chlorine reacts with natural organic matter in water.
Question 10
At the base of an elevated storage tank, a pressure gauge reads 72 psi. How far above the gauge
is the water surface?
A. 166 feet
B. 145 feet
C. 200 feet
D. 120 feet
Answer: A
Rationale: 1 psi = 2.31 feet of water. 72 psi × 2.31 ft/psi = 166.32 feet.
pg. 3
, Question 11
The most commonly used pump in the distribution system is:
A. Centrifugal
B. Frictional
C. Reciprocating
D. Ekman spiral
Answer: A
Rationale: Centrifugal pumps are the most common type used in water distribution systems due
to their efficiency and simplicity.
Question 12
When designing systems, engineers use a rule of thumb of ______ gallons per person per day
when more accurate data isn't available:
A. 150
B. 100
C. 130
D. 80
Answer: B
Rationale: The standard design flow is 100 gallons per person per day for residential use.
Question 13
A certified operator doing routine daily checks discovers a cut lock on the entry gate and a cut
lock on the roof hatch with suspicious containers. What should the operator do?
A. Immediately notify TCEQ Regional office; they will notify law enforcement and investigate
B. Pull the electrical disconnect on the pumps and close valves isolating the tank until analyzed
C. Enter the tank to investigate
D. Ignore it and continue routine checks
Answer: A
Rationale: The operator must immediately notify the TCEQ Regional Office, who will notify
law enforcement and investigate to determine if there is a danger or threat to public health and
safety.
Question 14
Waterlines should be installed no closer than ______ feet to any sewer lines or other possible
contaminant lines:
A. 500
B. 9
pg. 4
