DWV DESIGN – DRAIN, WASTE & VENT SYSTEMS VERIFIED EXAM SOLUTIONS - COMPREHENSIVE QUESTIONS AND ANSWERS - CURRENT VERSION (2026/2027)

DWV DESIGN – DRAIN, WASTE & VENT SYSTEMS VERIFIED EXAM
SOLUTIONS - COMPREHENSIVE QUESTIONS AND ANSWERS -
CURRENT VERSION (2026/2027)




1. What does DWV stand for in plumbing?
A) Drain, Waste, Vent
B) Drain, Water, Valve
C) Duct, Waste, Vent
D) Drain, Waste, Valve
✓ Correct Answer: A
2. What is the primary purpose of the vent system in DWV?
A) To supply fresh water
B) To maintain atmospheric pressure in drain pipes
C) To filter waste water
D) To heat water
✓ Correct Answer: B
3. Which of the following is NOT a component of a DWV system?
A) P-trap
B) Stack vent
C) Pressure regulator
D) Cleanout
✓ Correct Answer: C
4. What is the minimum slope required for horizontal drain pipes per IPC?
A) 1/16 inch per foot
B) 1/8 inch per foot
C) 1/4 inch per foot
D) 1/2 inch per foot
✓ Correct Answer: C
5. What is a 'stack' in DWV terminology?

, A) A horizontal drain pipe
B) A vertical drain pipe serving multiple floors
C) A pipe fitting
D) A vent cap
✓ Correct Answer: B
6. Which trap is most commonly used under sinks?
A) S-trap
B) P-trap
C) Bottle trap
D) Running trap
✓ Correct Answer: B
7. What is the function of a trap in a DWV system?
A) To increase water pressure
B) To prevent sewer gases from entering the building
C) To collect debris
D) To control water flow
✓ Correct Answer: B
8. What is the minimum trap seal depth required by most plumbing codes?
A) 1 inch
B) 2 inches
C) 3 inches
D) 4 inches
✓ Correct Answer: B
9. Which pipe material is most commonly used for residential DWV today?
A) Cast iron
B) Copper
C) PVC
D) Galvanized steel
✓ Correct Answer: C
10. What is the maximum trap seal depth allowed by most plumbing codes?
A) 2 inches
B) 3 inches
C) 4 inches
D) 6 inches

, ✓ Correct Answer: C

SECTION 2: VENTING
11. What is an 'air admittance valve' (AAV)?
A) A check valve for water supply
B) A one-way valve that allows air into drain pipes without a roof
penetration
C) A valve controlling air conditioning
D) A pressure relief valve
✓ Correct Answer: B
12. What is a 'wet vent'?
A) A vent pipe exposed to rain
B) A pipe that simultaneously serves as both a drain and a vent
C) A vent connected to the water supply
D) A submerged vent pipe
✓ Correct Answer: B
13. What is the minimum diameter for an individual vent pipe?
A) 1 inch
B) 1¼ inches
C) 1½ inches
D) 2 inches
✓ Correct Answer: B
14. What is a 'circuit vent'?
A) An electrical component
B) A vent serving a series of fixtures on a horizontal branch
C) A vent that loops back to the stack
D) A vent serving only one fixture
✓ Correct Answer: B
15. How far above the roof surface must a vent pipe terminate?
A) 2 inches
B) 4 inches
C) 6 inches
D) 12 inches
✓ Correct Answer: C

, 16. What is a 'loop vent'?
A) A vent that circles the building
B) A vent that connects back to the stack vent above the fixture drain
C) A vent used only for toilets
D) A vent loop under the slab
✓ Correct Answer: B
17. What is the minimum distance a vent must be from a door or window
opening?
A) 2 feet
B) 3 feet
C) 5 feet
D) 10 feet
✓ Correct Answer: B
18. What is a 'common vent'?
A) A shared vent in an apartment building
B) A single vent that serves two fixture drains
C) The main building vent
D) A vent open to the atmosphere
✓ Correct Answer: B
19. What is 'back-venting'?
A) Venting backward through the drain
B) An individual vent connecting a fixture trap to the vent system
C) A vent installed backwards
D) Reverse airflow in vent pipes
✓ Correct Answer: B
20. What is the maximum distance a toilet drain can be from a vent?
A) 4 feet
B) 6 feet
C) 8 feet
D) 10 feet
✓ Correct Answer: B

SECTION 3: DRAIN PIPES
21. What is the minimum drain pipe size for a toilet (water closet)?
A) 2 inches