InterNACHI - International Association of Certified Home Inspectors Plumbing Systems Inspection Questions and Answers

Question 1

An inspector, while evaluating a home's drain, waste, and vent (DWV) system, hears a distinct gurgling sound from the bathtub drain immediately after flushing a nearby toilet.
Both fixtures appear to drain adequately otherwise.
What is the most probable cause of this gurgling sound?

Accepted Answer

A partial blockage or inadequate plumbing vent.

Answer

Excessive water pressure in the supply lines.

Answer

A cracked toilet bowl.

Answer

The P-trap for the bathtub has lost its seal due to evaporation.

Question 2

What is the primary safety purpose of the Temperature and Pressure Relief (TPR) valve installed on a residential water heater?

Accepted Answer

To prevent dangerous pressure or temperature buildup by discharging water.

Answer

To allow the homeowner to easily drain the tank for routine maintenance.

Answer

To automatically regulate the daily operating temperature of the water.

Answer

To prevent sediment from accumulating at the bottom of the tank.

Question 3

During an inspection of a home built in 1988, an inspector identifies flexible, gray plastic water supply pipes stamped with "PB2110." This piping material is known as:

Accepted Answer

Polybutylene (PB)

Answer

Cross-linked polyethylene (PEX)

Answer

Chlorinated polyvinyl chloride (CPVC)

Answer

Acrylonitrile butadiene styrene (ABS)

Question 4

While inspecting a home's exterior, you observe a garden hose attached to a hose bibb with the other end of the hose lying submerged in a small, decorative pond. This situation represents a significant risk known as a:

Accepted Answer

Cross-connection with a potential for back-siphonage

Answer

Pressure differential failure

Answer

Hydraulic displacement defect

Answer

Thermal expansion overload

Question 5

According to common plumbing codes, a P-trap is installed at each fixture to block sewer gases from entering the home. What is the generally accepted minimum and maximum water seal depth for a standard P-trap?

Accepted Answer

2 inches minimum, 4 inches maximum

Answer

1 inch minimum, 3 inches maximum

Answer

4 inches minimum, 6 inches maximum

Answer

0.5 inches minimum, 2 inches maximum

Question 6

Which of the following actions is an inspector REQUIRED to perform during a plumbing inspection according to the InterNACHI Standards of Practice?

Accepted Answer

Describe the materials of the visible water supply and drain lines.

Answer

Determine the potability or quality of the water.

Answer

Operate any shut-off valves to confirm they are functional.

Answer

Measure the water pressure using a gauge.