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Water Works Operator Class C Licensing Exam Practice Test – 100 Questions And Correct Answers (Verified Answers) Plus Rationales 2026 Q&A | Instant Download Pdf
- What is the primary purpose of a distribution water system?
- To treat water to potable standards
- To store wastewater for treatment
- To move water from treatment plants to consumers
- To disinfect sewage
Answer: C
Rationale: Distribution systems deliver safe drinking water from the
treatment facility to users.
- Which of the following is the standard unit for measuring chlorine
dosage? 1 / 4
- mg/L
- g/L
- ppm/hour
- lbs/day
Answer: A
Rationale: Chlorine dosage in water treatment is commonly measured in
milligrams per liter (mg/L).
- What is the minimum chlorine residual required at the farthest point in
- 0.1 mg/L
- 0.2 mg/L
- 0.5 mg/L
- 1.0 mg/L
a distribution system?
Answer: B
Rationale: Most regulations require a detectable residual, typically at least
0.2 mg/L.
- Which device is used to measure water pressure?
- Flow meter
- Chlorinator
- Pressure gauge
- Hydrant wrench
Answer: C
Rationale: Pressure gauges directly measure system pressure in psi or kPa. 2 / 4
- What is the typical lifespan of a well pump in a water system?
- 1–3 years
- 3–5 years
- 7–10 years
- 20+ years
Answer: C
Rationale: Most well pumps last 7–10 years under normal operating
conditions.
6. Turbidity in drinking water primarily indicates the presence of:
- Viruses
- Suspended particles
- Dissolved minerals
- Organic gases
Answer: B
Rationale: Turbidity is caused by suspended solids that scatter light.
7. The best method to detect leaks in a distribution system is:
- Listening devices
- Ground-penetrating radar
- Visual inspection
- Water auditing and metering
Answer: D 3 / 4
Rationale: Water audits identify water losses and help pinpoint leak
locations.
- What is the typical pressure range in a distribution system?
- 0–10 psi
- 10–20 psi
- 40–80 psi
- 100–150 psi
Answer: C
Rationale: Most systems operate within 40–80 psi for safety and reliability.
- What is the first step when responding to a main break?
- Flush the system
- Add more chlorine
- Notify customers
- Isolate the break
Answer: D
Rationale: Isolating stops water loss and limits contamination.
10. Hardness in water is primarily caused by:
- Sodium and potassium
- Chlorine
- Nitrates
- Calcium and magnesium
- / 4
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