Home Inspector Plumbing DWV Systems Flashcards
7 cards from real Home Inspector Test practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Home Inspector Plumbing DWV Systems flashcards as text
What is the minimum diameter of a building drain that receives discharge from a toilet?
Answer: 3 inches
A toilet (water closet) requires a minimum 3-inch drain to accommodate solid waste without clogging.
A home inspector finds that the trap for a floor drain in the basement has no water in it. What hazard does this create?
Answer: Sewer gases can enter the living space
A dry trap has no water seal to block sewer gases, allowing hydrogen sulfide and methane to enter the building, creating health and safety hazards.
Under US plumbing codes, where must a building drain clean-out be located?
Answer: Near the connection to the public sewer and at the base of each vertical stack
Code typically requires a clean-out near where the building drain exits the foundation and at the base of each soil or waste stack for maintenance access.
Which of the following is a sign of a failed or missing trap primer on a floor drain?
Answer: Sewer odor in the room with the floor drain
A trap primer keeps infrequently used floor drain traps filled with water; without it the trap dries out and sewer gas enters the space.
An inspector finds PVC drain pipe installed below the slab without bedding material and resting directly on soil. What is the primary concern?
Answer: Uneven soil settlement can stress joints and cause leaks
Without proper bedding and backfill, differential soil movement can crack or separate PVC joints, leading to underground leaks that are costly to repair.
Which of the following is NOT a function of the DWV system?
Answer: Maintaining water supply pressure
Water supply pressure is managed by the supply system; the DWV system handles drainage, venting, and waste removal only.
A home inspector observes a 'S-trap' under a lavatory. Why is this considered a defect?
Answer: S-traps self-siphon and lose their water seal, allowing sewer gas entry
The S-trap's double-curve geometry creates a siphon effect that pulls the water seal out of the trap each time the fixture drains, eliminating the gas barrier.