Free 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.

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This free plumbing practice test includes 20 multiple-choice questions drawn from the subject areas covered on journeyman and master plumber licensing exams. Topics include water supply pipe materials and sizing, backflow prevention, DWV systems, trap requirements, venting methods, and plumbing code compliance.

After you submit, you will see your score, the correct answer for each question, and a plain-English explanation. Review missed questions to identify the code sections and trade concepts you need to study before your exam.

These questions are for study practice only and are not official exam questions. ExamsLib is not an official licensing authority. Passing this practice test does not guarantee a passing score on your state licensing exam.

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

Question 1

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

Question 2

Which fitting is prohibited in the horizontal plane of a drain line because it creates an abrupt direction change that allows solids to accumulate?

Question 3

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

Question 4

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

Question 5

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

Question 6

What is the primary purpose of a P-trap beneath a plumbing fixture?

Question 7

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 8

A temperature and pressure relief (T&P) valve discharge pipe on a water heater must terminate:

Question 9

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

Question 10

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

Question 11

A cleanout fitting in a drainage system is primarily installed to:

Question 12

An island sink vent is used when:

Question 13

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 14

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

Question 15

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

Question 16

Which backflow prevention method is required on an irrigation system where sprinkler heads can be submerged in contaminated water?

Question 17

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

Question 18

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

Question 19

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 20

When sizing a cold-water branch using the fixture-unit method, what additional factor must be accounted for beyond the total fixture unit count?

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Frequently asked questions

What topics does this plumbing practice test cover?

The practice test covers water supply systems (pipe materials, sizing, backflow prevention, water heaters), drain-waste-vent systems (traps, slope, venting methods, DWV sizing), and plumbing code requirements (UPC and IPC concepts, permits, fixture requirements).

Is this practice test the same as the real plumbing licensing exam?

No. These questions are for study practice only and are not official exam questions. The real licensing exam is administered by your state licensing board or its approved testing provider. ExamsLib is not an official licensing authority.

How many questions are on the free practice test?

This free practice test has 20 multiple-choice questions. A passing practice score is 70 percent or better (14 out of 20 correct).

Can I retake the practice test?

Yes. You can retake the practice test as many times as needed. A different set of questions may be assembled from the bank on each attempt, giving you fresh practice.

Do I need to create an account to take the practice test?

No account or login is required. The practice test is completely free and your results are saved locally in your browser.