CT Unlimited Plumbing Contractor (P-1)
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Reduce pipe diameter
Answer: B. Prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that prevents sewer
gases and odors from entering occupied spaces. The trap must be
properly sized, vented, and protected from siphonage or backpressure
so the water seal remains effective.
2. Which type of fitting is commonly used to change the direction of a
drainage pipe by 90 degrees?
,A. Sanitary tee
B. Coupling
C. Elbow
D. Reducer
Answer: C. Elbow
Rationale: An elbow is designed to change the direction of piping. In
drainage systems, the specific type of elbow matters because fittings
with excessive changes in direction can interfere with proper flow and
cleaning.
3. What is the primary function of a plumbing vent system?
A. Supply potable water
B. Remove solid waste
C. Protect trap seals and allow drainage system air circulation
D. Increase water temperature
Answer: C. Protect trap seals and allow drainage system air circulation
Rationale: Plumbing vents allow air to enter the drainage system and
help equalize pressure. Proper venting protects trap seals from
siphonage and backpressure while promoting reliable drainage.
4. Which pipe material is commonly used for potable cold-water
distribution systems?
,A. PVC
B. Cast iron soil pipe
C. ABS DWV
D. Clay tile
Answer: A. PVC
Rationale: PVC is commonly approved for potable water distribution
when the particular pipe and fittings are listed for that application.
DWV-rated materials, such as certain ABS products, should not
automatically be substituted for potable-water piping.
5. What does the term “water hammer” describe?
A. A reduction in water temperature
B. A pressure surge caused by sudden changes in water velocity
C. A leak caused by corrosion
D. A blockage in a sewer line
Answer: B. A pressure surge caused by sudden changes in water
velocity
Rationale: Water hammer occurs when flowing water is stopped or
redirected rapidly, producing a pressure wave. Properly designed
piping, secure supports, appropriate valves, and approved water-
hammer arrestors can help control the problem.
, 6. Which device is designed to prevent contaminated water from
flowing backward into a potable water supply?
A. Pressure regulator
B. Backflow preventer
C. Expansion tank
D. Air chamber
Answer: B. Backflow preventer
Rationale: Backflow preventers protect potable water systems from
contamination caused by backpressure or backsiphonage. The specific
type of protection depends on the hazard and system conditions.
7. What is the purpose of a cleanout in a drainage system?
A. Increase water pressure
B. Provide access for inspection and clearing blockages
C. Reduce pipe temperature
D. Prevent water evaporation
Answer: B. Provide access for inspection and clearing blockages
Rationale: Cleanouts provide access to drainage piping so
maintenance personnel can inspect, snake, or otherwise clear
obstructions. Their placement and accessibility are important for
effective maintenance.
Exam Questions and Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf
1. What is the primary purpose of a plumbing trap?
A. Increase water pressure
B. Prevent sewer gases from entering a building
C. Increase drainage velocity
D. Reduce pipe diameter
Answer: B. Prevent sewer gases from entering a building
Rationale: A plumbing trap retains a water seal that prevents sewer
gases and odors from entering occupied spaces. The trap must be
properly sized, vented, and protected from siphonage or backpressure
so the water seal remains effective.
2. Which type of fitting is commonly used to change the direction of a
drainage pipe by 90 degrees?
,A. Sanitary tee
B. Coupling
C. Elbow
D. Reducer
Answer: C. Elbow
Rationale: An elbow is designed to change the direction of piping. In
drainage systems, the specific type of elbow matters because fittings
with excessive changes in direction can interfere with proper flow and
cleaning.
3. What is the primary function of a plumbing vent system?
A. Supply potable water
B. Remove solid waste
C. Protect trap seals and allow drainage system air circulation
D. Increase water temperature
Answer: C. Protect trap seals and allow drainage system air circulation
Rationale: Plumbing vents allow air to enter the drainage system and
help equalize pressure. Proper venting protects trap seals from
siphonage and backpressure while promoting reliable drainage.
4. Which pipe material is commonly used for potable cold-water
distribution systems?
,A. PVC
B. Cast iron soil pipe
C. ABS DWV
D. Clay tile
Answer: A. PVC
Rationale: PVC is commonly approved for potable water distribution
when the particular pipe and fittings are listed for that application.
DWV-rated materials, such as certain ABS products, should not
automatically be substituted for potable-water piping.
5. What does the term “water hammer” describe?
A. A reduction in water temperature
B. A pressure surge caused by sudden changes in water velocity
C. A leak caused by corrosion
D. A blockage in a sewer line
Answer: B. A pressure surge caused by sudden changes in water
velocity
Rationale: Water hammer occurs when flowing water is stopped or
redirected rapidly, producing a pressure wave. Properly designed
piping, secure supports, appropriate valves, and approved water-
hammer arrestors can help control the problem.
, 6. Which device is designed to prevent contaminated water from
flowing backward into a potable water supply?
A. Pressure regulator
B. Backflow preventer
C. Expansion tank
D. Air chamber
Answer: B. Backflow preventer
Rationale: Backflow preventers protect potable water systems from
contamination caused by backpressure or backsiphonage. The specific
type of protection depends on the hazard and system conditions.
7. What is the purpose of a cleanout in a drainage system?
A. Increase water pressure
B. Provide access for inspection and clearing blockages
C. Reduce pipe temperature
D. Prevent water evaporation
Answer: B. Provide access for inspection and clearing blockages
Rationale: Cleanouts provide access to drainage piping so
maintenance personnel can inspect, snake, or otherwise clear
obstructions. Their placement and accessibility are important for
effective maintenance.
