Practice test

Free Plumbing Practice Test

Take our free plumbing practice test with 20 questions covering water supply, drainage and vent systems, and plumbing code. See your score instantly.

These questions are for study practice only and are not official exam questions.

Question 1

1

When dielectric unions are required between copper and galvanized steel pipe, their purpose is to:

Question 2

2

When connecting a horizontal branch drain to a vertical soil stack, which fitting orientation is required to prevent solids from being deposited at the junction?

Question 3

3

When a plumbing inspection is required by the permit, the inspector must be called:

Question 4

4

What is the purpose of a vent pipe in a drain-waste-vent (DWV) system?

Question 5

5

The maximum horizontal distance a trap arm may travel before connecting to a vent is limited to prevent:

Question 6

6

Which type of trap is prohibited by most plumbing codes because it retains solids, is difficult to vent properly, and has an unreliable seal?

Question 7

7

An air admittance valve (AAV) may NOT be used as the sole vent termination for an entire building's drainage system because:

Question 8

8

A horizontal drain pipe sloped more steeply than 1/2 inch per foot is generally discouraged for large-diameter pipes because:

Question 9

9

The term 'cross-connection' in plumbing refers to:

Question 10

10

Which pipe material is most commonly used for residential cold-water supply lines in modern construction?

Question 11

11

What device is installed on a water supply line to prevent contaminated water from flowing backward into the potable supply?

Question 12

12

A building has a measured static pressure of 50 psi at street level. Water loses approximately 0.43 psi per vertical foot of elevation. If the top-floor fixture is 60 feet above the meter, what is the approximate static pressure available at that fixture before any friction losses?

Question 13

13

A reduced pressure zone (RPZ) backflow preventer must be installed so that:

Question 14

14

Which pipe material requires separation from parallel steel gas piping to prevent electrolytic corrosion when both pipes share a common conductor path?

Question 15

15

What term describes the minimum vertical distance between a water outlet and the flood-level rim of a fixture that prevents backflow by creating a physical break?

Question 16

16

In a wet-vented system, what is generally required of the pipe that serves as both drain and vent simultaneously?

Question 17

17

Which type of valve provides full, unobstructed flow when open and is operated with a quarter turn, making it ideal as a shut-off valve?

Question 18

18

Who is typically responsible for obtaining a plumbing permit before a new water heater installation begins?

Question 19

19

What is the minimum slope typically required for a horizontal drain pipe that is 3 inches or smaller in diameter?

Question 20

20

A pressure-reducing valve (PRV) is generally required on an incoming water service when the static supply pressure exceeds:

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