TCEQ Class B Surface Water Exam
2026 – Newest Verified Questions
& Detailed Answers Study Guide
Table of Contents
• Section 1: Basic Water Treatment Concepts (Questions 1-10)
• Section 2: Water Chemistry and Quality Parameters (Questions 11-25)
• Section 3: Disinfection and Chlorination (Questions 26-40)
• Section 4: Pumps, Hydraulics, and Distribution Systems (Questions 41-50)
• Section 5: Coagulation, Flocculation, and Sedimentation (Questions 51-60)
• Section 6: Filtration Processes (Questions 61-70)
• Section 7: Distribution System Operations (Questions 71-78)
• Section 8: Regulations, Safety, and Reporting (Questions 79-90)
• Section 9: Troubleshooting and Advanced Operations (Questions 91-100)
Basic Water Treatment Concepts
Question 1
How does temperature affect chlorine effectiveness?
A) Chlorine is more effective at lower temperatures
B) Chlorine effectiveness is greater at higher temperatures, up to the point that
chlorine volatizes
C) Temperature has no effect on chlorine disinfection
D) Chlorine works best at freezing temperatures
CORRECT ANSWER>>>B) Chlorine effectiveness is greater at higher
temperatures, up to the point that chlorine volatizes
,Rationale: At higher temperatures, chlorine is more effective as a disinfectant
because chemical reactions occur faster. However, if the temperature becomes
too high, chlorine can volatilize (turn into gas) and escape from the water. At low
temperatures, chlorine is more stable but requires longer contact time for
effective disinfection .
Question 2
Why is removing turbidity important for disinfection?
A) Turbidity adds color to the water
B) Turbidity must be removed to low levels by sedimentation and filtration to
allow chlorine to contact pathogens
C) Turbidity helps chlorine work better
D) Turbidity is required for proper disinfection
CORRECT ANSWER>>>B) Turbidity must be removed to low levels by
sedimentation and filtration to allow chlorine to contact pathogens
Rationale: Turbidity consists of suspended particles that can shield
microorganisms from chlorine's disinfecting action. Pathogens can become
embedded within or attached to these particles, preventing chlorine from
reaching and destroying them. Effective removal of turbidity through
sedimentation and filtration ensures that chlorine can directly contact and
inactivate pathogens .
Question 3
What happens to dissolved solids on contact with chlorine?
A) They are unchanged
B) They are oxidized, reinforcing the importance of contact time
C) They become more concentrated
D) They precipitate out of solution
CORRECT ANSWER>>>B) They are oxidized, reinforcing the importance of
contact time
,Rationale: When chlorine contacts dissolved solids (such as iron, manganese,
hydrogen sulfide, and organic compounds), it oxidizes them. This oxidation
process consumes chlorine and requires adequate contact time to complete. This
reinforces why contact time is a critical factor in the disinfection process—
sufficient time must be allowed for chlorine to both oxidize interfering substances
and destroy pathogens .
Question 4
What is Turbidity?
A) The color of water
B) A measure of the relative clarity of water, causing light to be scattered and
absorbed
C) The temperature of water
D) The pH level of water
CORRECT ANSWER>>>B) A measure of the relative clarity of water, causing light
to be scattered and absorbed
Rationale: Turbidity is an expression of the optical property that causes light to be
scattered and absorbed rather than transmitted in straight lines through a water
sample. It measures the relative clarity of water and indicates the presence of
suspended particles .
Question 5
What causes Turbidity?
A) Dissolved salts only
B) Clay, silt, finely divided organic and inorganic material, and microscopic
organisms
C) Temperature changes only
D) Chlorine residual
CORRECT ANSWER>>>B) Clay, silt, finely divided organic and inorganic material,
and microscopic organisms
, Rationale: Turbidity is caused by various suspended materials including clay, silt,
finely divided organic and inorganic material, and microscopic organisms. The
approved method for measuring turbidity is the Nephelometric Method, with
results reported in Nephelometric Turbidity Units (NTU) .
Question 6
What is meant by water stability?
A) Water that remains at constant temperature
B) Water that will neither deposit nor dissolve a calcium carbonate film or scale
C) Water with stable pH
D) Water that never changes composition
CORRECT ANSWER>>>B) Water that will neither deposit nor dissolve a calcium
carbonate film or scale
Rationale: Stable water is defined as water that will neither deposit nor dissolve a
calcium carbonate film or scale. Since no water is stable indefinitely, chemical
treatment usually aims to produce water that is slightly scale-forming without
causing stoppages in small lines and services. The Bayliss curve is the simplest
determination of stability, while the Langelier Saturation Index is also used .
Question 7
What is the Texas drinking water pH requirement?
A) pH must be exactly 7.0
B) pH must be less than 7.0
C) pH must be greater than 7.0 for finished water
D) pH has no requirement
CORRECT ANSWER>>>C) pH must be greater than 7.0 for finished water
Rationale: Texas drinking water regulations require a pH greater than 7.0 for
finished water leaving the treatment plant. Additionally, the EPA requires that pH
analysis be performed within 15 minutes of sample collection .
2026 – Newest Verified Questions
& Detailed Answers Study Guide
Table of Contents
• Section 1: Basic Water Treatment Concepts (Questions 1-10)
• Section 2: Water Chemistry and Quality Parameters (Questions 11-25)
• Section 3: Disinfection and Chlorination (Questions 26-40)
• Section 4: Pumps, Hydraulics, and Distribution Systems (Questions 41-50)
• Section 5: Coagulation, Flocculation, and Sedimentation (Questions 51-60)
• Section 6: Filtration Processes (Questions 61-70)
• Section 7: Distribution System Operations (Questions 71-78)
• Section 8: Regulations, Safety, and Reporting (Questions 79-90)
• Section 9: Troubleshooting and Advanced Operations (Questions 91-100)
Basic Water Treatment Concepts
Question 1
How does temperature affect chlorine effectiveness?
A) Chlorine is more effective at lower temperatures
B) Chlorine effectiveness is greater at higher temperatures, up to the point that
chlorine volatizes
C) Temperature has no effect on chlorine disinfection
D) Chlorine works best at freezing temperatures
CORRECT ANSWER>>>B) Chlorine effectiveness is greater at higher
temperatures, up to the point that chlorine volatizes
,Rationale: At higher temperatures, chlorine is more effective as a disinfectant
because chemical reactions occur faster. However, if the temperature becomes
too high, chlorine can volatilize (turn into gas) and escape from the water. At low
temperatures, chlorine is more stable but requires longer contact time for
effective disinfection .
Question 2
Why is removing turbidity important for disinfection?
A) Turbidity adds color to the water
B) Turbidity must be removed to low levels by sedimentation and filtration to
allow chlorine to contact pathogens
C) Turbidity helps chlorine work better
D) Turbidity is required for proper disinfection
CORRECT ANSWER>>>B) Turbidity must be removed to low levels by
sedimentation and filtration to allow chlorine to contact pathogens
Rationale: Turbidity consists of suspended particles that can shield
microorganisms from chlorine's disinfecting action. Pathogens can become
embedded within or attached to these particles, preventing chlorine from
reaching and destroying them. Effective removal of turbidity through
sedimentation and filtration ensures that chlorine can directly contact and
inactivate pathogens .
Question 3
What happens to dissolved solids on contact with chlorine?
A) They are unchanged
B) They are oxidized, reinforcing the importance of contact time
C) They become more concentrated
D) They precipitate out of solution
CORRECT ANSWER>>>B) They are oxidized, reinforcing the importance of
contact time
,Rationale: When chlorine contacts dissolved solids (such as iron, manganese,
hydrogen sulfide, and organic compounds), it oxidizes them. This oxidation
process consumes chlorine and requires adequate contact time to complete. This
reinforces why contact time is a critical factor in the disinfection process—
sufficient time must be allowed for chlorine to both oxidize interfering substances
and destroy pathogens .
Question 4
What is Turbidity?
A) The color of water
B) A measure of the relative clarity of water, causing light to be scattered and
absorbed
C) The temperature of water
D) The pH level of water
CORRECT ANSWER>>>B) A measure of the relative clarity of water, causing light
to be scattered and absorbed
Rationale: Turbidity is an expression of the optical property that causes light to be
scattered and absorbed rather than transmitted in straight lines through a water
sample. It measures the relative clarity of water and indicates the presence of
suspended particles .
Question 5
What causes Turbidity?
A) Dissolved salts only
B) Clay, silt, finely divided organic and inorganic material, and microscopic
organisms
C) Temperature changes only
D) Chlorine residual
CORRECT ANSWER>>>B) Clay, silt, finely divided organic and inorganic material,
and microscopic organisms
, Rationale: Turbidity is caused by various suspended materials including clay, silt,
finely divided organic and inorganic material, and microscopic organisms. The
approved method for measuring turbidity is the Nephelometric Method, with
results reported in Nephelometric Turbidity Units (NTU) .
Question 6
What is meant by water stability?
A) Water that remains at constant temperature
B) Water that will neither deposit nor dissolve a calcium carbonate film or scale
C) Water with stable pH
D) Water that never changes composition
CORRECT ANSWER>>>B) Water that will neither deposit nor dissolve a calcium
carbonate film or scale
Rationale: Stable water is defined as water that will neither deposit nor dissolve a
calcium carbonate film or scale. Since no water is stable indefinitely, chemical
treatment usually aims to produce water that is slightly scale-forming without
causing stoppages in small lines and services. The Bayliss curve is the simplest
determination of stability, while the Langelier Saturation Index is also used .
Question 7
What is the Texas drinking water pH requirement?
A) pH must be exactly 7.0
B) pH must be less than 7.0
C) pH must be greater than 7.0 for finished water
D) pH has no requirement
CORRECT ANSWER>>>C) pH must be greater than 7.0 for finished water
Rationale: Texas drinking water regulations require a pH greater than 7.0 for
finished water leaving the treatment plant. Additionally, the EPA requires that pH
analysis be performed within 15 minutes of sample collection .
