PC Plumber Water & Drainage 3 — Questions and Answers
Question 1: What is the minimum size of a building sewer that serves a single-family home under the IPC?
- 2 inches
- 3 inches
- 4 inches (Correct answer)
- 6 inches
Correct answer: 4 inches
The IPC requires a minimum 4-inch diameter building sewer for a residential structure.
Question 2: What is the term for negative pressure in a drain system that pulls water out of fixture traps?
- Back pressure
- Siphonage (Correct answer)
- Water hammer
- Hydraulic jump
Correct answer: Siphonage
Siphonage is the negative pressure (vacuum) that pulls trap water seals out, allowing sewer gases to enter the building.
Question 3: A plumber installs a dishwasher drain. Where must the drain hose be routed before connecting to the drain or disposal?
- Directly through the cabinet floor
- In a high loop or through an air gap above the flood level rim of the sink (Correct answer)
- Through a P-trap before the disposal
- Directly to the floor drain
Correct answer: In a high loop or through an air gap above the flood level rim of the sink
A dishwasher drain must be looped high under the counter or use an air gap to prevent back-siphonage of contaminated water into the dishwasher.
Question 4: What type of vent serves as both a drain and a vent for the same fixture?
- Wet vent (Correct answer)
- Common vent
- Circuit vent
- Relief vent
Correct answer: Wet vent
A wet vent serves simultaneously as a vent for one fixture and a drain for another fixture connected above it.
Question 5: Under the IPC, what is the minimum water pressure required at the point of use for a residential fixture?
- 15 psi
- 20 psi (Correct answer)
- 40 psi
- 60 psi
Correct answer: 20 psi
The IPC requires a minimum of 20 psi at the point of delivery for any plumbing fixture.
Question 6: What is the correct way to orient a sanitary tee when used in a horizontal drain line?
- Outlet pointing up (upright) (Correct answer)
- Outlet pointing down (inverted)
- Outlet at 45 degrees
- Outlet pointing horizontally
Correct answer: Outlet pointing up (upright)
Sanitary tees must be installed upright (outlet pointing up) in horizontal drain lines to direct flow toward the vertical stack.
Question 7: Which material is NOT approved for use as a DWV (drain, waste, and vent) pipe under the IPC?
- ABS plastic
- PVC plastic
- CPVC (Correct answer)
- Cast iron
Correct answer: CPVC
CPVC is a pressure pipe material approved for hot and cold water supply but is not listed for use in DWV applications.
PC Plumber Water & Drainage 3
What is the minimum size of a building sewer that serves a single-family home under the IPC?