TCEQ Class C Water License Practice
Questions & Answers (Study Guide) with
Accurate Solutions (Verified)
1. What state agency is responsible for enforcing the Safe Drinking
Water Act in Texas?
A. Texas Department of State Health Services
B. Environmental Protection Agency
C. Texas Commission on Environmental Quality
D. Texas Water Development Board
✅ Correct Answer: C
Explanation:
The Texas Commission on Environmental Quality (TCEQ) enforces the
Safe Drinking Water Act within Texas. TCEQ oversees public water
systems, operator licensing, compliance inspections, and enforcement
actions. The EPA sets national standards but delegates enforcement
authority to the state.
2. What minerals commonly cause water hardness?
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and manganese
D. Chloride and sulfate
✅ Correct Answer: B
Explanation:
Water hardness is caused primarily by calcium and magnesium ions
dissolved in water. These minerals enter groundwater as it moves through
limestone and other mineral deposits. Hard water causes scale buildup and
reduces soap effectiveness.
3. A public water system must at all times provide:
,A. Bottled water during outages
B. Fluoridated water only
C. Adequate quantity, pressure, and disinfection
D. Surface water treatment
✅ Correct Answer: C
Explanation:
Public water systems are required to continuously provide adequate water
quantity, pressure, and proper disinfection. These elements ensure water is
safe for consumption and available for domestic and fire protection needs.
Failure to meet these standards is a regulatory violation.
4. A groundwater source of supply is obtained from a(n):
A. Reservoir
B. Lake
C. River
D. Aquifer
✅ Correct Answer: D
Explanation:
Groundwater is stored in underground formations called aquifers. These
formations consist of permeable materials like sand, gravel, or fractured
rock. Wells are drilled into aquifers to supply drinking water.
5. Fecal coliform organisms in water indicate:
A. High mineral content
B. Proper disinfection
C. Possible contamination and harmful bacteria
D. Excess chlorine residual
✅ Correct Answer: C
,Explanation:
Fecal coliform bacteria indicate contamination from human or animal
waste. Their presence suggests disease-causing organisms may also be
present. Water testing positive for fecal coliforms is considered unsafe for
drinking.
6. Which disease may be spread by inadequately disinfected water?
A. Influenza
B. Dysentery
C. Measles
D. Tuberculosis
✅ Correct Answer: B
Explanation:
Dysentery is a waterborne illness caused by bacteria or parasites found in
contaminated water. Inadequate disinfection allows these pathogens to
survive. Proper chlorination greatly reduces the risk of waterborne disease.
7. A common disinfectant used in small water systems is:
A. Chlorine gas
B. Ozone
C. Calcium hypochlorite
D. Chloramines
✅ Correct Answer: C
Explanation:
Calcium hypochlorite is widely used in small systems because it is safer to
store and handle than chlorine gas. It is a solid compound that releases
chlorine when dissolved. It provides effective disinfection when properly
dosed.
, 8. A physical connection between a potable water supply and a house
well is a:
A. Backflow device
B. Service connection
C. Cross-connection
D. Air gap
✅ Correct Answer: C
Explanation:
A cross-connection is any physical link between potable and non-potable
water systems. This connection can allow contaminants to enter the
drinking water supply. Cross-connections must be eliminated or protected
by approved backflow prevention.
9. Chlorine demand is defined as:
A. Chlorine remaining after 30 minutes
B. Amount of chlorine added
C. Chlorine used up by reactions before residual forms
D. Free chlorine residual
✅ Correct Answer: C
Explanation:
Chlorine demand is the amount of chlorine consumed by reactions with
organic matter, iron, manganese, and microorganisms. Only after demand
is satisfied does a chlorine residual remain. Understanding demand
ensures proper disinfection.
10. Which is a physical characteristic of chlorine gas?
Questions & Answers (Study Guide) with
Accurate Solutions (Verified)
1. What state agency is responsible for enforcing the Safe Drinking
Water Act in Texas?
A. Texas Department of State Health Services
B. Environmental Protection Agency
C. Texas Commission on Environmental Quality
D. Texas Water Development Board
✅ Correct Answer: C
Explanation:
The Texas Commission on Environmental Quality (TCEQ) enforces the
Safe Drinking Water Act within Texas. TCEQ oversees public water
systems, operator licensing, compliance inspections, and enforcement
actions. The EPA sets national standards but delegates enforcement
authority to the state.
2. What minerals commonly cause water hardness?
A. Sodium and potassium
B. Calcium and magnesium
C. Iron and manganese
D. Chloride and sulfate
✅ Correct Answer: B
Explanation:
Water hardness is caused primarily by calcium and magnesium ions
dissolved in water. These minerals enter groundwater as it moves through
limestone and other mineral deposits. Hard water causes scale buildup and
reduces soap effectiveness.
3. A public water system must at all times provide:
,A. Bottled water during outages
B. Fluoridated water only
C. Adequate quantity, pressure, and disinfection
D. Surface water treatment
✅ Correct Answer: C
Explanation:
Public water systems are required to continuously provide adequate water
quantity, pressure, and proper disinfection. These elements ensure water is
safe for consumption and available for domestic and fire protection needs.
Failure to meet these standards is a regulatory violation.
4. A groundwater source of supply is obtained from a(n):
A. Reservoir
B. Lake
C. River
D. Aquifer
✅ Correct Answer: D
Explanation:
Groundwater is stored in underground formations called aquifers. These
formations consist of permeable materials like sand, gravel, or fractured
rock. Wells are drilled into aquifers to supply drinking water.
5. Fecal coliform organisms in water indicate:
A. High mineral content
B. Proper disinfection
C. Possible contamination and harmful bacteria
D. Excess chlorine residual
✅ Correct Answer: C
,Explanation:
Fecal coliform bacteria indicate contamination from human or animal
waste. Their presence suggests disease-causing organisms may also be
present. Water testing positive for fecal coliforms is considered unsafe for
drinking.
6. Which disease may be spread by inadequately disinfected water?
A. Influenza
B. Dysentery
C. Measles
D. Tuberculosis
✅ Correct Answer: B
Explanation:
Dysentery is a waterborne illness caused by bacteria or parasites found in
contaminated water. Inadequate disinfection allows these pathogens to
survive. Proper chlorination greatly reduces the risk of waterborne disease.
7. A common disinfectant used in small water systems is:
A. Chlorine gas
B. Ozone
C. Calcium hypochlorite
D. Chloramines
✅ Correct Answer: C
Explanation:
Calcium hypochlorite is widely used in small systems because it is safer to
store and handle than chlorine gas. It is a solid compound that releases
chlorine when dissolved. It provides effective disinfection when properly
dosed.
, 8. A physical connection between a potable water supply and a house
well is a:
A. Backflow device
B. Service connection
C. Cross-connection
D. Air gap
✅ Correct Answer: C
Explanation:
A cross-connection is any physical link between potable and non-potable
water systems. This connection can allow contaminants to enter the
drinking water supply. Cross-connections must be eliminated or protected
by approved backflow prevention.
9. Chlorine demand is defined as:
A. Chlorine remaining after 30 minutes
B. Amount of chlorine added
C. Chlorine used up by reactions before residual forms
D. Free chlorine residual
✅ Correct Answer: C
Explanation:
Chlorine demand is the amount of chlorine consumed by reactions with
organic matter, iron, manganese, and microorganisms. Only after demand
is satisfied does a chlorine residual remain. Understanding demand
ensures proper disinfection.
10. Which is a physical characteristic of chlorine gas?
