These 5 questions cover supply and drain piping, water heaters, fixtures and cross-connections. On the National Home Inspector Examination they fall under Property Inspection (70% of the exam). Try each one before you open the answer: the explanation matters more than the letter.
1. Under a kitchen sink the inspector finds a small plastic cap-shaped device on the drain line in place of a vent to the roof. The inspector should identify this as
- a cleanout plug that was left loose on the drain
- an air admittance valve giving one-way venting
- a backflow preventer fitted on the drain line
- a trap primer feeding a nearby floor drain
Show answer
Answer: B. an air admittance valve giving one-way venting
An air admittance valve (AAV) opens under negative pressure to let air into the drain and closes to block sewer gas, substituting for a conventional vent where permitted. It must be accessible, installed above the trap weir, and is not allowed in every jurisdiction or situation.
Memory tip: AAV: lets air in, keeps gas out.
2. A garden hose is connected to an exterior faucet with no vacuum breaker and its end lies in a bucket of fertilizer solution. The MOST significant concern is
- fertilizer could siphon into the potable supply
- the hose will reduce pressure at other fixtures
- the faucet packing will leak under the load
- the bucket will overflow and flood the area
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Answer: A. fertilizer could siphon into the potable supply
Backflow is the reversal of flow that allows contaminants into the potable supply. A submerged hose end with no backflow protection is a classic cross-connection; a drop in supply pressure can siphon the bucket contents into the house piping.
Memory tip: Hose in a bucket = cross-connection.
3. The dishwasher drain hose runs level along the cabinet floor to the disposer. The MOST appropriate recommendation is to
- replace the hose with rigid copper pipe
- shorten the hose to the minimum length needed
- secure a high loop under the counter or add an air gap
- connect the hose to the sink tailpiece instead
Show answer
Answer: C. secure a high loop under the counter or add an air gap
A high loop secured as high as possible under the counter, or a listed air gap device, prevents drain water from flowing back into the dishwasher. A level or low-run hose provides no protection and is a common correctable defect.
Memory tip: High loop or air gap—one or the other.
4. A rural property is served by a private well. The inspector should
- test the well yield and sample the water quality
- report the private well as a plumbing deficiency
- decline to inspect the plumbing system entirely
- run the fixtures; note the well itself is out of scope
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Answer: D. run the fixtures; note the well itself is out of scope
Private water supply systems—wells, pumps, and treatment—are typically excluded from Standards of Practice. The inspector operates fixtures to check functional flow, describes the water source, and recommends specialist evaluation and water testing as appropriate.
Memory tip: Well water: test it elsewhere.
5. A laundry tub faucet spout extends below the flood rim of the tub. This condition should be reported because
- the spout will corrode below the water line
- the spout needs an air gap above the flood rim
- the tub cannot drain with the spout that low
- the faucet is the wrong type for a laundry tub
Show answer
Answer: B. the spout needs an air gap above the flood rim
An air gap is the vertical space between the spout outlet and the flood-level rim of the fixture, typically at least twice the pipe diameter and never less than one inch. A spout below the rim allows contaminated water to backflow if the tub fills and supply pressure drops.
Memory tip: Spout stays above the rim.