NYC Health + Hospitals Supervising
Plumber Examination Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Supply hot water
C. Protect trap seals and allow proper drainage-system airflow
D. Reduce pipe diameter
Answer: Protect trap seals and allow proper drainage-system airflow
Rationale: A properly designed vent system permits air movement through the
drainage system and protects trap seals from siphonage and backpressure.
2. Which fitting is generally preferred for changing direction in a sanitary
drainage system?
A. Sanitary tee on its back
B. Long-sweep elbow
C. Straight coupling
D. Reducing bushing
,Answer: Long-sweep elbow
Rationale: Long-sweep fittings provide smoother flow and reduce the likelihood
of obstruction in drainage piping.
3. What is the primary function of a water trap?
A. Increase water temperature
B. Prevent sewer gases from entering occupied spaces
C. Increase water pressure
D. Remove sediment from water
Answer: Prevent sewer gases from entering occupied spaces
Rationale: The water seal in a trap acts as a barrier against sewer gases while
still allowing wastewater to discharge.
4. A supervisor discovers that a worker is about to enter an excavation with an
unsafe, unsupported wall. What should the supervisor do first?
A. Allow the worker to continue
B. Stop the work and correct the hazard
C. Increase the water pressure
D. Ignore the condition if the excavation is shallow
Answer: Stop the work and correct the hazard
Rationale: A supervising plumber is responsible for maintaining safe work
practices and should immediately address a potentially life-threatening
excavation hazard.
5. What is the purpose of a cleanout in a drainage system?
A. Increase water pressure
B. Provide access for inspection and removal of blockages
C. Heat the drainage pipe
D. Prevent water from entering the pipe
,Answer: Provide access for inspection and removal of blockages
Rationale: Cleanouts provide service access to drainage piping so that
obstructions can be located and removed.
6. Which device is commonly used to prevent contaminated water from
flowing backward into a potable water supply?
A. Pressure gauge
B. Backflow prevention device
C. Expansion joint
D. Water hammer arrestor
Answer: Backflow prevention device
Rationale: Backflow prevention devices protect potable water from
contamination caused by backsiphonage or backpressure.
7. What condition occurs when negative pressure causes contaminated water
to be drawn backward into a potable system?
A. Thermal expansion
B. Backsiphonage
C. Water hammer
D. Cavitation
Answer: Backsiphonage
Rationale: Backsiphonage occurs when a drop in supply pressure creates a
suction effect that can draw contaminants into the potable water system.
8. What is the primary purpose of a pressure-reducing valve?
A. Increase water temperature
B. Lower excessive downstream water pressure
C. Remove sewage
D. Vent a drainage system
, Answer: Lower excessive downstream water pressure
Rationale: A pressure-reducing valve regulates excessive incoming pressure to a
safer downstream pressure.
9. What is water hammer?
A. A type of pipe corrosion
B. A pressure surge caused by a rapid change in water velocity
C. A method of pipe joining
D. A sewer ventilation technique
Answer: A pressure surge caused by a rapid change in water velocity
Rationale: Rapidly closing valves can abruptly stop flowing water, creating a
pressure wave that produces noise, vibration, and potentially damaging forces.
10.Which component is commonly installed to control water hammer near
quick-closing valves?
A. Trap primer
B. Water hammer arrestor
C. Cleanout
D. Vacuum breaker
Answer: Water hammer arrestor
Rationale: Water hammer arrestors absorb pressure surges caused by sudden
changes in water velocity.
11.What is the purpose of a trap primer?
A. Maintain water in a trap
B. Increase boiler pressure
C. Reduce pipe corrosion
D. Increase drainage velocity
Answer: Maintain water in a trap
Plumber Examination Practice Exam
2026 | 100 Questions & Answers with
Detailed Rationales | Complete Exam
Prep & Study Guide
1. What is the primary purpose of a plumbing vent system?
A. Increase water pressure
B. Supply hot water
C. Protect trap seals and allow proper drainage-system airflow
D. Reduce pipe diameter
Answer: Protect trap seals and allow proper drainage-system airflow
Rationale: A properly designed vent system permits air movement through the
drainage system and protects trap seals from siphonage and backpressure.
2. Which fitting is generally preferred for changing direction in a sanitary
drainage system?
A. Sanitary tee on its back
B. Long-sweep elbow
C. Straight coupling
D. Reducing bushing
,Answer: Long-sweep elbow
Rationale: Long-sweep fittings provide smoother flow and reduce the likelihood
of obstruction in drainage piping.
3. What is the primary function of a water trap?
A. Increase water temperature
B. Prevent sewer gases from entering occupied spaces
C. Increase water pressure
D. Remove sediment from water
Answer: Prevent sewer gases from entering occupied spaces
Rationale: The water seal in a trap acts as a barrier against sewer gases while
still allowing wastewater to discharge.
4. A supervisor discovers that a worker is about to enter an excavation with an
unsafe, unsupported wall. What should the supervisor do first?
A. Allow the worker to continue
B. Stop the work and correct the hazard
C. Increase the water pressure
D. Ignore the condition if the excavation is shallow
Answer: Stop the work and correct the hazard
Rationale: A supervising plumber is responsible for maintaining safe work
practices and should immediately address a potentially life-threatening
excavation hazard.
5. What is the purpose of a cleanout in a drainage system?
A. Increase water pressure
B. Provide access for inspection and removal of blockages
C. Heat the drainage pipe
D. Prevent water from entering the pipe
,Answer: Provide access for inspection and removal of blockages
Rationale: Cleanouts provide service access to drainage piping so that
obstructions can be located and removed.
6. Which device is commonly used to prevent contaminated water from
flowing backward into a potable water supply?
A. Pressure gauge
B. Backflow prevention device
C. Expansion joint
D. Water hammer arrestor
Answer: Backflow prevention device
Rationale: Backflow prevention devices protect potable water from
contamination caused by backsiphonage or backpressure.
7. What condition occurs when negative pressure causes contaminated water
to be drawn backward into a potable system?
A. Thermal expansion
B. Backsiphonage
C. Water hammer
D. Cavitation
Answer: Backsiphonage
Rationale: Backsiphonage occurs when a drop in supply pressure creates a
suction effect that can draw contaminants into the potable water system.
8. What is the primary purpose of a pressure-reducing valve?
A. Increase water temperature
B. Lower excessive downstream water pressure
C. Remove sewage
D. Vent a drainage system
, Answer: Lower excessive downstream water pressure
Rationale: A pressure-reducing valve regulates excessive incoming pressure to a
safer downstream pressure.
9. What is water hammer?
A. A type of pipe corrosion
B. A pressure surge caused by a rapid change in water velocity
C. A method of pipe joining
D. A sewer ventilation technique
Answer: A pressure surge caused by a rapid change in water velocity
Rationale: Rapidly closing valves can abruptly stop flowing water, creating a
pressure wave that produces noise, vibration, and potentially damaging forces.
10.Which component is commonly installed to control water hammer near
quick-closing valves?
A. Trap primer
B. Water hammer arrestor
C. Cleanout
D. Vacuum breaker
Answer: Water hammer arrestor
Rationale: Water hammer arrestors absorb pressure surges caused by sudden
changes in water velocity.
11.What is the purpose of a trap primer?
A. Maintain water in a trap
B. Increase boiler pressure
C. Reduce pipe corrosion
D. Increase drainage velocity
Answer: Maintain water in a trap
