Illinois Class C Water Operator
certification Exam With Actual Questions
& Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass 2025/2026 /Latest
Update/Instant Download Pdf
1. What is the primary purpose of a groundwater well sanitary seal?
• A. To increase pumping capacity
• B. To prevent equipment vibration
• C. To prevent surface contamination
• D. To improve water clarity
Answer: C. To prevent surface contamination
Rationale: A sanitary seal is installed at the top of a well to prevent contaminants from
entering the well from the surface or shallow subsurface layers.
2. Which federal agency enforces the Safe Drinking Water Act?
• A. Environmental Protection Agency (EPA)
• B. Centers for Disease Control (CDC)
• C. Department of the Interior (DOI)
• D. Occupational Safety and Health Administration (OSHA)
Answer: A. Environmental Protection Agency (EPA)
Rationale: The EPA enforces the Safe Drinking Water Act to ensure public water supplies
meet health standards.
3. In groundwater treatment, what is the main purpose of chlorination?
, • A. Iron removal
• B. pH adjustment
• C. Turbidity reduction
• D. Disinfection
Answer: D. Disinfection
Rationale: Chlorination is used to kill or inactivate pathogenic microorganisms, making
water safe for consumption.
4. What is the function of a well casing?
• A. To pump water
• B. To maintain the well opening and prevent collapse
• C. To filter water
• D. To store water
Answer: B. To maintain the well opening and prevent collapse
Rationale: A well casing supports the well structure and prevents the surrounding soil from
collapsing into the well.
5. What chemical is used to determine if a chlorine cylinder is leaking?
• A. Ammonia
• B. Chlorine
• C. Sodium hydroxide
• D. Potassium permanganate
Answer: A. Ammonia
Rationale: Ammonia vapor is passed near the valve; the presence of a leak is indicated by
white smoke.
6. Bacteria and viruses that cause disease or illness are called:
• A. Pathogens
• B. Pathogens
• C. Contaminants
, • D. Pollutants
Answer: B. Pathogens
Rationale: Pathogens are microorganisms that can cause diseases in humans.
7. Drinking water is usually tested for what?
• A. Total solids
• B. Total coliforms
• C. pH levels
• D. Fluoride content
Answer: B. Total coliforms
Rationale: Testing for total coliforms helps detect potential contamination and assess water
quality.
8. The membrane filter procedure takes how many day(s) to complete?
• A. One
• B. Two
• C. One
• D. Three
Answer: C. One
Rationale: The membrane filter procedure is a rapid method for detecting coliform bacteria,
typically completed in one day.
9. What is a coupon?
• A. A discount voucher
• B. A section of water main removed during a tap
• C. A type of valve
• D. A water quality test kit
Answer: B. A section of water main removed during a tap
Rationale: A coupon is a piece of pipe removed when making a tap to inspect the condition
of the main.
certification Exam With Actual Questions
& Verified Answers,Plus
Rationales/Expert Verified For
Guaranteed Pass 2025/2026 /Latest
Update/Instant Download Pdf
1. What is the primary purpose of a groundwater well sanitary seal?
• A. To increase pumping capacity
• B. To prevent equipment vibration
• C. To prevent surface contamination
• D. To improve water clarity
Answer: C. To prevent surface contamination
Rationale: A sanitary seal is installed at the top of a well to prevent contaminants from
entering the well from the surface or shallow subsurface layers.
2. Which federal agency enforces the Safe Drinking Water Act?
• A. Environmental Protection Agency (EPA)
• B. Centers for Disease Control (CDC)
• C. Department of the Interior (DOI)
• D. Occupational Safety and Health Administration (OSHA)
Answer: A. Environmental Protection Agency (EPA)
Rationale: The EPA enforces the Safe Drinking Water Act to ensure public water supplies
meet health standards.
3. In groundwater treatment, what is the main purpose of chlorination?
, • A. Iron removal
• B. pH adjustment
• C. Turbidity reduction
• D. Disinfection
Answer: D. Disinfection
Rationale: Chlorination is used to kill or inactivate pathogenic microorganisms, making
water safe for consumption.
4. What is the function of a well casing?
• A. To pump water
• B. To maintain the well opening and prevent collapse
• C. To filter water
• D. To store water
Answer: B. To maintain the well opening and prevent collapse
Rationale: A well casing supports the well structure and prevents the surrounding soil from
collapsing into the well.
5. What chemical is used to determine if a chlorine cylinder is leaking?
• A. Ammonia
• B. Chlorine
• C. Sodium hydroxide
• D. Potassium permanganate
Answer: A. Ammonia
Rationale: Ammonia vapor is passed near the valve; the presence of a leak is indicated by
white smoke.
6. Bacteria and viruses that cause disease or illness are called:
• A. Pathogens
• B. Pathogens
• C. Contaminants
, • D. Pollutants
Answer: B. Pathogens
Rationale: Pathogens are microorganisms that can cause diseases in humans.
7. Drinking water is usually tested for what?
• A. Total solids
• B. Total coliforms
• C. pH levels
• D. Fluoride content
Answer: B. Total coliforms
Rationale: Testing for total coliforms helps detect potential contamination and assess water
quality.
8. The membrane filter procedure takes how many day(s) to complete?
• A. One
• B. Two
• C. One
• D. Three
Answer: C. One
Rationale: The membrane filter procedure is a rapid method for detecting coliform bacteria,
typically completed in one day.
9. What is a coupon?
• A. A discount voucher
• B. A section of water main removed during a tap
• C. A type of valve
• D. A water quality test kit
Answer: B. A section of water main removed during a tap
Rationale: A coupon is a piece of pipe removed when making a tap to inspect the condition
of the main.
