2025 TEXAS CLASS D WATER LICENSE (COMPLETE)
QUESTIONS AND ANSWERS!!
Question 1
Which state agency in Texas is responsible for enforcing the Safe Drinking
Water Act and administering water operator licensing?
A) Environmental Protection Agency (EPA)
B) Texas Department of State Health Services (DSHS)
C) Texas Commission on Environmental Quality (TCEQ)
D) Public Utility Commission of Texas (PUC)
E) Texas Water Development Board (TWDB)
Correct Answer: C) Texas Commission on Environmental Quality (TCEQ)
Rationale: The TCEQ is the primary state regulator of water utilities and is
responsible for enforcing drinking water standards and licensing water
operators in Texas.
Question 2
What is the primary purpose of disinfection in a public water system?
A) To remove suspended solids from the water.
B) To adjust the pH of the water.
C) To kill or inactivate pathogenic microorganisms.
D) To remove undesirable tastes and odors.
E) To reduce water hardness.
Correct Answer: C) To kill or inactivate pathogenic microorganisms.
Rationale: Disinfection is a critical treatment process specifically designed to
destroy or inactivate disease-causing bacteria, viruses, and other pathogens
in the water, making it safe to drink.
Question 3
A "potable" water supply is defined as water that is:
A) Suitable for irrigation only.
B) Visually clear and free of turbidity.
C) Safe to drink and has a measurable chlorine residual.
D) Used only for industrial purposes.
,E) High in mineral content.
Correct Answer: C) Safe to drink and has a measurable chlorine
residual.
Rationale: Potable water means it is safe for human consumption and
typically includes a measurable chlorine residual to ensure ongoing
disinfection in the distribution system.
Question 4
Which of the following describes the percentage of Earth's surface covered
by water?
A) Approximately 50%
B) Approximately 60%
C) Approximately 71%
D) Approximately 85%
E) Approximately 90%
Correct Answer: C) Approximately 71%
Rationale: Water covers approximately 71% of Earth's surface.
Question 5
What is the most important federal law impacting the water utility industry?
A) Clean Water Act (CWA)
B) Endangered Species Act (ESA)
C) Safe Drinking Water Act (SDWA)
D) Resource Conservation and Recovery Act (RCRA)
E) Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA)
Correct Answer: C) Safe Drinking Water Act (SDWA)
Rationale: The Safe Drinking Water Act is the primary federal law that sets
standards for drinking water quality and protects public health.
Question 6
Which two minerals are primarily responsible for causing water hardness?
A) Sodium and Potassium
,B) Iron and Manganese
C) Magnesium and Calcium
D) Chloride and Sulfate
E) Lead and Copper
Correct Answer: C) Magnesium and Calcium
Rationale: Magnesium and Calcium are the most common minerals that
cause water hardness.
Question 7
The term "residual" in the context of water treatment refers to:
A) The amount of water lost due to leaks in the distribution system.
B) The amount of chlorine left in the water after the demand has been met.
C) The amount of suspended solids remaining after filtration.
D) The total dissolved solids content of the water.
E) The amount of water used for flushing mains.
Correct Answer: B) The amount of chlorine left in the water after the
demand has been met.
Rationale: Residual chlorine is the amount of disinfectant remaining in the
water after disinfection demand has been satisfied, ensuring continued
protection.
Question 8
A Class D Water Operator license in Texas is valid for how many years?
A) 1 year
B) 2 years
C) 3 years
D) 4 years
E) 5 years
Correct Answer: C) 3 years
Rationale: A Class D Water Operator license is valid for 3 years, according to
TCEQ regulations.
, Question 9
What are the physical characteristics of water that an operator might assess?
A) pH, alkalinity, hardness.
B) Bacteria, viruses, protozoa.
C) Color, taste, odor, temperature, turbidity.
D) Lead, copper, iron, manganese.
E) Chlorine residual, fluoride, nitrates.
Correct Answer: C) Color, taste, odor, temperature, turbidity.
Rationale: These are observable properties of water that do not involve
chemical reactions or biological tests.
Question 10
An alkaline or basic solution has a pH greater than:
A) 1
B) 3
C) 7
D) 10
E) 14
Correct Answer: C) 7
Rationale: The pH scale ranges from 0-14, with 7 being neutral. A pH greater
than 7 indicates an alkaline or basic solution.
Question 11
In water utility math, the terms mg/L and ppm are:
A) Not interchangeable.
B) Interchangeable and mean parts per million.
C) Only used for chlorine calculations.
D) Only used for turbidity measurements.
E) Primarily used in wastewater treatment.
Correct Answer: B) Interchangeable and mean parts per million.
Rationale: For water and wastewater calculations, milligrams per liter (mg/L)
QUESTIONS AND ANSWERS!!
Question 1
Which state agency in Texas is responsible for enforcing the Safe Drinking
Water Act and administering water operator licensing?
A) Environmental Protection Agency (EPA)
B) Texas Department of State Health Services (DSHS)
C) Texas Commission on Environmental Quality (TCEQ)
D) Public Utility Commission of Texas (PUC)
E) Texas Water Development Board (TWDB)
Correct Answer: C) Texas Commission on Environmental Quality (TCEQ)
Rationale: The TCEQ is the primary state regulator of water utilities and is
responsible for enforcing drinking water standards and licensing water
operators in Texas.
Question 2
What is the primary purpose of disinfection in a public water system?
A) To remove suspended solids from the water.
B) To adjust the pH of the water.
C) To kill or inactivate pathogenic microorganisms.
D) To remove undesirable tastes and odors.
E) To reduce water hardness.
Correct Answer: C) To kill or inactivate pathogenic microorganisms.
Rationale: Disinfection is a critical treatment process specifically designed to
destroy or inactivate disease-causing bacteria, viruses, and other pathogens
in the water, making it safe to drink.
Question 3
A "potable" water supply is defined as water that is:
A) Suitable for irrigation only.
B) Visually clear and free of turbidity.
C) Safe to drink and has a measurable chlorine residual.
D) Used only for industrial purposes.
,E) High in mineral content.
Correct Answer: C) Safe to drink and has a measurable chlorine
residual.
Rationale: Potable water means it is safe for human consumption and
typically includes a measurable chlorine residual to ensure ongoing
disinfection in the distribution system.
Question 4
Which of the following describes the percentage of Earth's surface covered
by water?
A) Approximately 50%
B) Approximately 60%
C) Approximately 71%
D) Approximately 85%
E) Approximately 90%
Correct Answer: C) Approximately 71%
Rationale: Water covers approximately 71% of Earth's surface.
Question 5
What is the most important federal law impacting the water utility industry?
A) Clean Water Act (CWA)
B) Endangered Species Act (ESA)
C) Safe Drinking Water Act (SDWA)
D) Resource Conservation and Recovery Act (RCRA)
E) Comprehensive Environmental Response, Compensation, and Liability Act
(CERCLA)
Correct Answer: C) Safe Drinking Water Act (SDWA)
Rationale: The Safe Drinking Water Act is the primary federal law that sets
standards for drinking water quality and protects public health.
Question 6
Which two minerals are primarily responsible for causing water hardness?
A) Sodium and Potassium
,B) Iron and Manganese
C) Magnesium and Calcium
D) Chloride and Sulfate
E) Lead and Copper
Correct Answer: C) Magnesium and Calcium
Rationale: Magnesium and Calcium are the most common minerals that
cause water hardness.
Question 7
The term "residual" in the context of water treatment refers to:
A) The amount of water lost due to leaks in the distribution system.
B) The amount of chlorine left in the water after the demand has been met.
C) The amount of suspended solids remaining after filtration.
D) The total dissolved solids content of the water.
E) The amount of water used for flushing mains.
Correct Answer: B) The amount of chlorine left in the water after the
demand has been met.
Rationale: Residual chlorine is the amount of disinfectant remaining in the
water after disinfection demand has been satisfied, ensuring continued
protection.
Question 8
A Class D Water Operator license in Texas is valid for how many years?
A) 1 year
B) 2 years
C) 3 years
D) 4 years
E) 5 years
Correct Answer: C) 3 years
Rationale: A Class D Water Operator license is valid for 3 years, according to
TCEQ regulations.
, Question 9
What are the physical characteristics of water that an operator might assess?
A) pH, alkalinity, hardness.
B) Bacteria, viruses, protozoa.
C) Color, taste, odor, temperature, turbidity.
D) Lead, copper, iron, manganese.
E) Chlorine residual, fluoride, nitrates.
Correct Answer: C) Color, taste, odor, temperature, turbidity.
Rationale: These are observable properties of water that do not involve
chemical reactions or biological tests.
Question 10
An alkaline or basic solution has a pH greater than:
A) 1
B) 3
C) 7
D) 10
E) 14
Correct Answer: C) 7
Rationale: The pH scale ranges from 0-14, with 7 being neutral. A pH greater
than 7 indicates an alkaline or basic solution.
Question 11
In water utility math, the terms mg/L and ppm are:
A) Not interchangeable.
B) Interchangeable and mean parts per million.
C) Only used for chlorine calculations.
D) Only used for turbidity measurements.
E) Primarily used in wastewater treatment.
Correct Answer: B) Interchangeable and mean parts per million.
Rationale: For water and wastewater calculations, milligrams per liter (mg/L)
