This free plumbing practice test will give you an idea of the types of questions that appear on actual plumbing licensing exams. Plumbing exams vary by state but most all states and local plumbing jurisdictions have adopted either the IPC or the UPC plumbing codes. Typical exam sections include: fixtures, sanitary drainage systems, administrative policies, venting, indirect and special wastes, etc.


Administrative Policies and Procedures

1. A plumbing permit is required for the replacement of which of the following?
a. Water closet

b. Water heater
c. Bathing unit
d. Faucet

A plumbing permit is not needed for the direct replacement of any plumbing fixture, except for a water heater. However, if a fixture location is changed, a permit is required. In other words, you can remove a toilet and replace it with a new one without the need for a permit. But, if you move the closest flange in any way, a permit is required. This is true for all plumbing fixtures.

2. The provisions for licensing are determined by which of the following:
a. State Board of Plumbing

b. Authority having jurisdiction
c. Plumbing inspector
d. The responsible master plumber

The authority having jurisdiction determines the provisions for licensing. State Plumbing Boards determine requirements and provide testing of qualified applicants to become licensed. Plumbing inspectors enforce codes adopted by the AHJ.

General Regulations

3. Which of the following is suitable for testing a DWV system for leaks?
a. Air
b. Water
c. Smoke

d. All of the above

It is common for modern DWV systems to be tested with air. In the old days water was the most common means of testing. When there is a leak that cannot be found easily, smoke can be used to expose the leak location. Smoke is not used as a primary test method. Air is the test medium of choice. The testing of a DWV system is to be conducted for a minimum of 15 minutes. The minimum test pressure is required to be 10 pounds per square inch (PSI). If only underground plumbing is being tested there must be one riser that is at least ten feet above the main plumbing system.

4. All pipe used in plumbing applications will have all of the following markings except:
a. Pressure rating in psi
b. Nominal pipe size

c. Length of pipe
d. Manufacturer’s brand name

Some pipe manufacturers list measurement in one foot increments when rolls of pipe are 100′ or over, but do not list increments on joints of 21′, 20′ or less. Brand names, psi rating, and nominal pipe size are required.


5. What is the likely height of a handicap toilet?
a. 13 inches
b. 15 inches

c. 18 inches
d. 22 inches

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Handicap toilets are available with heights that include 16 inches, 18 inches and 20 inches. Eighteen inches is the most common height of a standard handicap toilet.

6. What is the minimum unobstructed opening of egress when a shower door is installed for a typical shower?

a. 22 inches
b. 24 inches
c. 28 inches
d. 30 inches

The minimum unobstructed opening of egress for a shower door installed on a typical shower is 22 inches.

Indirect and Special Wastes

7. Which of the following is considered to be the best method for connecting an indirect waste to a sanitary drainage system?

a. Air gap
b. Air break
c. Both a and b are equal
d. None of the above

An air gap is believed to be superior to an air break for the protection of an indirect wastepipe from back siphonage. Due to the nature of installation there is more risk of a backflow occurring with an air break. Since air breaks have discharge piping entering a receptor it is feasible to have the sanitary drain become clogged and back up, which could result in contaminated waste traveling back to the indirect waste fixture. This is not possible when an air gap is used.

8. The minimum vertical distance from the bottom of an indirect drain line to its receptor’s flood rim is _____________________________.

a. 1″
b. ¾”
c. ½”
d. 2″

Minimum vertical distance from the bottom of an indirect drain line to its receptors flood rim is 1″.

Vents and Venting

9. Which of the following types of fixtures can be served by a combination-waste-and-vent system?
a. Urinals
b. Toilets

c. Sinks
d. Bidets

Combination-waste-and vent (CWV) systems do not require independent vents on all fixtures. Instead of a vertical vent the fixtures approved for a CWV installation are installed with oversized drains. Due to the larger drain diameter the fixture obtains the needed air for drainage in the top section of the oversized piping. Urinals, toilets and bidets are not allowed to be installed on CWV systems.

10. You are connecting two back to back lavatories, two urinals and two water closets to one horizontal branch. What are the maximum number fixtures that can be connected to a horizontal branch?
a. 3
b. 4
c. 6

d. 8

The plumbing code allows a maximum of eight fixtures connections to a horizontal branch drain. This is also called a circuit vent.

11. Piping for building drains and horizontal drainage branches require the installation of cleanouts. Spacing for these cleanouts is determined by the diameter of the drain and other factors. In this scenario the drain pipe diameter is three inches. This drain has a running length of 77 feet. During this run the pipe takes one 90-degree turn. How many cleanouts are required for this installation?
a. 2

b. 3
c. 4
d. 6

Drain pipes with diameters of four inches, or less, are required to have cleanouts installed at a maximum distance of 50 feet apart. In our example this requires two cleanouts for this rule. A cleanout is also required when the pipe changes direction with an angle greater than 45 degrees. Since this pipe installation has a 90-degree bend another cleanout is required. Therefore, a total of three cleanouts are required.

Traps and Cleanouts

12. One trap arm may serve a total of how many P-traps?
a. 3

b. 1
c. 2
d. 4

Not more than one trap is permitted on a trap arm.

13. Flexible water connections are required to be _________.
a. Readily accessible

b. Accessible
c. Limited to first-floor installations
d. Supported

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All flexible water connections are required to be accessible. This means that they can be concealed in a cabinet or behind an access panel, but they must be accessible.

Water Supply and Distribution

14. Water heaters, hose bibs and sill cocks are normally protected from backflow with ________.
a. An air gap
b. An air break

c. A vacuum breaker
d. A reduced-pressure backflow preventer

Vacuum breakers are normally used to protect water heaters, sill cocks and hose bibs from backflow dangers.

Sanitary Drainage Systems

15. What is the typical amount of grade required per liner foot on a household drainage pipe?
a. 1/8 inch

b. 1/4 inch
c. 3/4 inch
d. 1 inch

The amount of grade, also referred to as pitch or fall, for a drain pipe is determined by the size of the drain pipe. Master plumbers and other design professional establish these elements of a plumbing system based on the minimum standards required by local code requirements. As a general rule-of thumb, the proper amount of grade for a drain up to 4-inches in diameter is .25 inch per liner foot.

16. What will result when a 4 inch pipe is reduced in size in the direction of the flow?
a. The waste will travel faster which will allow for better cleaning of the pipe.

b. This could cause blockage to build up at the reduction point.
c. This could cause slugging in the waste system.
d. This will have no affect on the drainage system.

At the reduction point, because of the direction of flow, waste can build up which will result in ping system blockage.

Special Piping and Storage Systems

17. In Med Gas systems, the exhaust from vacuum pumps must be discharged into the following:
a. Designated receptor
b. Indirect drain

c. Outdoors
d. Relief vent

Exhaust must be discharged outdoors in a way which will minimize the hazard of noise
and contamination to the environment.

18. Flux can only be used in the brazing process when:

a. Brazing copper to brass
b. Brazing copper to copper
c. Not allowed
d. Both a and b

Flux may only be used to braze dissimilar metals.

Water Heaters

19. Where is the maximum allowable working pressure of a storage tank and water heater required to be shown?
a. In the installation guide
b. Stamped in the metal
c. On a permanently attached plate

d. Either b or c

Such markings shall be in an accessible position outside of the tank, permanently affixed.

20. The minimum depth thickness for a water heater drip pan is __________________________.
a. 1″

b. 1.5″
c. 3/4″
d. 2″

1.5″ is the minimum depth size for a drip pan.

Recycling Gray Water

21. Gray water that enters a collection reservoir must be ________.
a. Measured
b. Flow controlled

c. Filtered
d. Monitored

Any gray water going into a gray-water collection reservoir is required to be filtered. This is required as a means of blocking solids from entering the collection reservoir. While the fixtures allowed for the recycling of gray water should not be transporting solids there is always a possibility the some type of solid could find its way into the drainage water. The filters stop these impurities from reaching the collection of gray water that will be recycled.

22. What is the maximum amount of time that gray water is allowed to be retained for use to flush a toilet or urinal?
a. 24 hours
b. 48 hours

c. 72 hours
d. 96 hours

The maximum allowable time for the retention of gray water that will be used to flush toilets or urinals is 72 hours. Holding water for long periods of time can result in the growth of bacteria. This bacteria is not wanted in the plumbing system. For example, green water in a toilet tank is not appealing and could present health hazards. When a gray water recycling system is sized properly the water retained in a collection reservoir would be balanced to the fixtures served and the normal daily use of the fixtures will draw down from the reservoir often enough to avoid prolonged water storage.

Fuel Gas

23. Gas piping installed in a laundry chute ____________.
a. Must be secured at maximum intervals of 6 feet
b. Must be protected from damage in the normal course of use of the chute
c. Is required to be installed with only vertical pipe sections

d. Is a code violation

Gas piping in not allowed to be installed in laundry chutes, dumbwaiters, air-circulating ducts or elevators. The chutes, shafts and ducts can transport gas to various locations in a building if a leak should occur. Therefore, it is inappropriate to install gas piping in a location that could distribute gas beyond the location of the leak.

24. When flow controls are installed on gas piping, they _____________.
a. Must be accessible
b. Must not contain sediment traps
c. Must be equipped with a leak-limiting device

d. Are used to keep operating pressure lower than the supply pressure

Flow controls on gas systems are installed to keep the operating pressure of the system lower than the supply pressure for the system. These devices prevent excessive pressure from the distribution system. They must be approved and suitable both the inlet and outlet gas pressure for the application. The flow controls must be readily accessible.


25. What is the angle made when you offset a sewer with a 1/8 bend?

a. 45°
b. 60°
c. 72°
d. 90°

Degree of Angle = Fitting x 360 Degrees
Degree of Angle = 0.125 x 360 Degrees
Degree of Angle = 45 degrees

26. What is the total pressure in pound per square inch (psi) on a 6 inch diameter test plug with a water head of 15 feet?
a. 3.00 psi
b. 4.25 psi

c. 6.51 psi
d. 7.20 psi

Pressure = Height x Amount of pressure exerted at base of a one foot stack
P = 15 x .434
P = 6.51 psi

Also Read:  CBT ARAMCO :: QA/QC - Instrumentation Inspector | Qualification Guideline | Vol-ll

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