2025 Edition

Master Plumber Practice Test

This Free Master Plumber Practice Test will give you an idea of the types of questions and sections on your actual exam.

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Admin. Policies & Procedures

1.	As a master plumber you will be allowed to apply for plumbing permits. Which of the following data will you be required to provide on a plumbing permit application?
		a. Your full name and address
		b. A full description of the plumbing work you propose to do
		c. The zoned use of the property where the plumbing will be installed
		d. All of the above
The application for a plumbing permit requires key information that you, as the master plumber applying for the permit, must supply. Information needed for the application will include the following: Applicant's full name Applicant's complete address A full description of all work to be performed The number of plumbing fixtures to be installed The type of plumbing fixtures to be installed The type of use of the structure where the plumbing is being installed Additional data may also be required, such as your plumbing license number, detailed plans and specifications and so forth. Incorrect answer. Please choose another answer.

2.	For the issuance of a plumbing permit, which of the following is normally required?
		a. Design plans
		b. Complete specifications
		c. A description of the use of the building
		d. All of the above
		e. Both a and b only
When you apply for a plumbing permit you must provide a full description of the work to be done. Plumbing plans are often required for larger jobs. Specifications of all materials to be installed are a common requirement for a plumbing permit. Permit applications require the physical address of the property to receive plumbing services. The use of the property is often required. It makes a difference if a structure is a home or a daycare. The owner's name of the proper is generally required. You are also required to detail the number and type of plumbing fixtures to be installed. Incorrect answer. Please choose another answer.

3.	If alterations are made in an existing plumbing system, the work is required to bring the entire existing plumbing system up to current code requirements.
		True
		False
Plumbing alterations should comply with current code requirements. The alterations made must be in compliance with present code requirements. However, the remainder of the existing plumbing system is not required to be upgraded to modern code requirements. Incorrect answer. Please choose another answer.

General Regulations

4.	Your job requires you to schedule maintenance on a large commercial building for one of your customers. What is the required frequency for the inspection of backflow preventers?
		a. Once a month
		b. Once every 3 months
		c. Once every 4 months
		d. Once every year
Annual inspections are required for backflow assemblies. Each backflow preventer should be tested during the inspection. They must be working properly and must not allow contamination to the water source in a water distribution system. New installations are required to be inspected. Any need to repair a backflow preventer triggers the need for a test and inspection of the repaired device. Incorrect answer. Please choose another answer.

5.	When working with engineered trusses, you must be aware of certain limitations that do not apply to trusses made of dimensional lumber. For example, an engineered truss must not be ___________________.
		a. spliced
		b. drilled
		c. cut or notched
		d. All of the above
Engineered trusses limit your ability to route piping. Trusses that are engineered must not be cut, notched, drilled, spliced or otherwise altered. If any alteration of a truss is essential, an engineer should be consulted to render specific instructions on what may be done to accommodate a plumbing installation. Incorrect answer. Please choose another answer.

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6.	Mechanical joints are an acceptable means of joining materials of different types.
		True
		False
Mechanical joints are a recommended means of making connections between dissimilar types of materials. They can also be used to join like materials. Incorrect answer. Please choose another answer.

Fixtures

7.	What is the maximum distance that employees can be required to walk in order to reach a restroom?
		a. 150 feet
		b. 300 feet
		c. 400 feet
		d. 500 feet
Five-hundred feet is the maximum allowable distance that employees can be required to walk in order to reach a restroom. Incorrect answer. Please choose another answer.

8.	What is the minimum allowable height for a handicap toilet?
		a. 14 inches
		b. 16 inches
		c. 18 inches
		d. 22 inches
Handicap toilets are required to have a minimum height of 16 inches. The most common accessible toilets have a height of 18 inches. In extreme cases, you can obtain and install a toilet that enjoys a height of 20 inches. Eighteen inches is the most common height of a standard handicap toilet. Incorrect answer. Please choose another answer.

9.	Accessible lavatories are required to be installed so that the distance from a finished floor to the top of a lavatory is no more than ______ inches.
		a. 18
		b. 24
		c. 35
		d. 42
Accessible lavatories are to be installed so that the top of the lavatory is never more than 35 inches above the finished floor beneath the lavatory. The measurement is made from the flood-level rim of the fixture to the finished floor. Incorrect answer. Please choose another answer.

Indirect & Special Wastes

10.	Discharge tubing connected to a relief valve does not require traps for which of the following?
		a. A water heaters
		b. A boiler
		c. An expansion tank that serves a boiler
		d. All of the above
The discharge tubing that is connected to a relief valve that is servicing a water heater, boiler or an expansion tank for a boiler is not allowed to be trapped. Discharge piping from the relief valve is to extend downward to a point within six inches of a floor. Ideally, the drainage tubing should terminate above a floor drain, but this is not a requirement. The end of the tubing is not to be threaded. Incorrect answer. Please choose another answer.

11.	You are in charge of a rough-in installation. The specifications given to you indicate the need for an indirect waste receptor. Upon further reflection, you notice a code violation in the specifications. The specs call for a fixture that is not normally allowed in a room with an indirect waster receptor. You are going to investigate this with the person who created the specifications. What type of fixture is it that you are questioning?
		a. Floor drain
		b. Food preparation equipment
		c. Toilet
		d. Kitchen sink
Indirect wastes are not normally allowed to be installed in rooms that contain toilets. Of course, code officers can issue variances. The only common exception is the installation of an indirect waste receptor for an automatic clothes washer. When you see an indirect waster called for in a room where a toilet will be installed you should verify the clearance for the work to be done. Incorrect answer. Please choose another answer.

12.	What is the maximum allowable water temperature that can be used with a commercial dishwashing machine?
		a. 115 degrees F
		b. 120 degrees F
		c. 140 degrees F
		d. None of the above
Commercial dishwashing machines are allowed to use high-temperature hot water that would not be allowed for a residential use. It is common for these machines to use hot water that has a temperature in excess of 140 degrees F. Due to the high temperature of hot water used with commercial equipment the discharge from the dishwasher must discharge through either an air gap or an air break. The discharge is to enter a standpipe made of approved materials for the high-temperature water. Incorrect answer. Please choose another answer.

Vents and Venting

13.	When multiple fixtures discharge into a wet vent they must do so upstream of the wet vent.
		True
		False
Drainage that enters a wet vent must enter the piping system downstream of the wet vent. For example, you might install a wye fitting and extend a drain horizontally to fixtures. The drains from the fixtures must tie into the drainage system prior to the pipe changing into a vent. The fact that the developed length of the pipe serves as both a drain and a vent makes it a wet vent. Incorrect answer. Please choose another answer.

14.	What type of vent is only allowed to convey air and sewer gas?
		a. A wet vent
		b. A stack vent
		c. A vent stack
		d. An island vent
Many types of vents can carry waste in their lower sections as drains and still provide the services of a vent. However, vent stacks must only be used as vent pipes. They are not allowed to accept drainage from plumbing fixtures. This type of vent is considered to be a primary vent. The vent is to extend to open air above the building containing it. While a vent stack is not allowed to accept drainage, it is acceptable to tie other vents into the vertical vent stack. Incorrect answer. Please choose another answer.

15.	What is the minimum allowable diameter for a vent that will serve a sump for a sewer pump that has a discharge capacity of 500 gpm?
		a. 2 inch
		b. 3 inch
		c. 4 inch
		d. 6 inch
Once the discharge capacity of a sewage pump reaches 500 gpm, the smallest allowable vent that can be used to vent the sewage sump is three inches in diameter. It is limited to 24 feet of developed length. If a 4-inch vent is used the developed length extends to 130 feet. Incorrect answer. Please choose another answer.

Traps and Cleanouts

16.	Drain pipes that are not building drains or horizontal branches that are installed in second-story framing are _________.
		a. required to have accessible cleanouts
		b. required to have no less than one cleanout at the end of the run of piping
		c. not required to be equipped with cleanouts
		d. not required to be equipped with cleanouts when the building drain is four inches, or larger, in diameter.
Drain pipes that are not building drains or horizontal branches that are installed in second-story framing are not required to be equipped with cleanouts. This is due to the fact that P-traps and toilets are allowed to act as required cleanouts. Incorrect answer. Please choose another answer.

17.	What type of drain requires the installation of a cleanout when two eighth bends are used to create a 90-degree change in direction?
		a. A drain serving a water closet or urinal
		b. Cleanouts are not required when changes in direction are made with eighth bends.
		c. A drain that is below the main floor level of habitable space
		d. A drain that receives the waste from a garbage disposer
Cleanouts are not required when changes in direction are made with eighth bends or other fittings with less of an angle than an eighth bend. This is due to the moderate rate of the change in direction. Incorrect answer. Please choose another answer.

18.	Only brass or plastic plugs can be used for sealing cleanout openings.
		True
		False
The plumbing code requires plugs used with cleanouts to be constructed of either brass or plastic. These are the only two types of material that are allowed for use as plugs to seal cleanouts. Incorrect answer. Please choose another answer.

Water Supply & Distribution

19.	Which of the following do you need in order to size water piping for a water distribution system?
		a. The rate at which the water will flow
		b. The minimum quantity of water that a pipe of a specific material can deliver
		c. The outside diameter of the pipe being used to deliver water
		d. The amount of pitch that will be installed on the supply piping
		e. Both a and d
In order to size a water distribution system you will need to know the flow rate of the water, the inside diameter of the water pipe and the amount of water that will be in the pipe. Once you know these three elements you can size a pipe with a fairly simple formula. This formula is done as follows: X = the water flow Y = the amount of water in the pipe Z = the inside diameter of the pipe Y =XZ Once you know the answer to the equation you can determine the size of the pipe requirement to meet the needs of a water supply pipe. But, there is an easier way. Most plumbers use the fixture-unit rating requirements of fixtures supplies to determine the piping size required for a full water distribution system. The plumbing code takes into account that plumbers do not generally want to be mathematicians, so tables and charts can be found in your code book that will allow you to size piping without the heavy math. Incorrect answer. Please choose another answer.

20.	A minimum distance of 100 feet is required between a pasture and a potable water well.
		True
		False
The minimum allowable distance between potable water wells and pastures is 100 feet. The well must be protected from contamination. Having 100 feet between a well and a pasture is intended to prevent runoff from the pasture from contaminating the water well. Incorrect answer. Please choose another answer.

21.	Carbonated beverage dispensers require the installation of ______________ on the incoming water supply.
		a. a vacuum breaker
		b. a butterfly-style backflow preventer
		c. a pneumatic backflow preventer
		d. a vented backflow preventer that is not affected by carbon dioxide gas if the fixture does not have an internal backflow preventer.
Carbonated beverage dispensers require the installation of a vented backflow preventer that is not affected by carbon dioxide gas. This can be an internal backflow preventer or one that is installed on the incoming water supply. Most carbonators are equipped with approved, manufacturer-installed backflow prevention devices. Incorrect answer. Please choose another answer.

Sanitary Drainage Systems

22.	Sizing procedures for sewers is done with the same practices and principles that are used when sizing ________________.
		a. horizontal branches
		b. soil stacks
		c. vent stacks
		d. building drains
Sewers and building drains are sized using the same sizing criteria. Horizontal branches are sized in a similar fashion, but the data used for sizing horizontal branches is different from what would be used for a sewer or a building drain. The minimum diameter for a pipe that will convey waste from a water closet is three inches. A 3-inch sewer installed with a slope of 1/4 inch per foot can carry up to 42 fixture units. If a 4-inch sewer is used under the same conditions it can handle up to 216 fixture units. Incorrect answer. Please choose another answer.

23.	Assume you are installing drainage piping in and around a food service area. Which of the following locations are not allowed to have exposed drainage piping installed above them?
		a. Areas used for storage
		b. Surfaces provided for eating
		c. Work areas
		d. All of the above
		e. B and c only
Due to the risk of leakage and potential contamination, exposed drainage piping is not allowed to be installed above work areas, storage areas or eating surfaces in or around food service areas. Incorrect answer. Please choose another answer.

24.	Suppose you want to turn a vertical drain to a horizontal position. Which of the following fittings cannot be used for this purpose?
		a. Quarter bend
		b. Short-sweep fittings
		c. Short-turn elbow
		d. Sanitary tee
You cannot use a sanitary tee for a change in direction from a vertical position to a horizontal position. Incorrect answer. Please choose another answer.

Special Piping & Storage Systems

25.	All fixtures and fittings installed in rooms housing psychiatric patients must be ________.
		a. supplied with only cold water
		b. firmly bolted to a fixed location
		c. protected from possible vandalism
		d. hospital approved
Plumbers are required to install fixtures and fittings used in psychiatric patient rooms so that the components are not subject to vandalism. This can mean using durable fixtures and concealing piping. The ultimate goal is to design and install a safe plumbing system that will serve the needs of the people using the plumbing. Incorrect answer. Please choose another answer.

26.	Suction equipment that is supplied with water falls under the same regulations of the plumbing code that pertains to aspirators.
		True
		False
Aspirators and suction equipment are both required to comply with the same code requirements when the suction equipment is supplied with water. In essence, the water supply must be protected from backflow. A vacuum breaker is the most common type of backflow preventer used for this purpose. Incorrect answer. Please choose another answer.

27.	Drains from sterilizers must be connected to a drainage system through an indirect-waste connection.
		True
		False
It is true that the drains conveying waste from sterilizers are required to be connected to drainage systems through indirect-waste connections. Incorrect answer. Please choose another answer.

Water Heaters

28.	Imagine that you are called upon to install a water heater for a triplex rental property. The water heater will be used for domestic purposes. Which of the following is required for the satisfactory installation?
		a. An indirect waste and drain pan
		b. An indelibly stamped metal plate that is permanently attached to the water heater in a clear and conspicuous location that shows the maximum working pressure of the water heater
		c. Pipe insulation on the inlet and outlet piping that extends a minimum of 18 inches above the water heater
		d. A stop and waste valve on the cold-water inlet pipe
		e. Both b and d
Water heaters for domestic use are to have the water heater's maximum working pressure clearly and indelibly attached in a permanent manner to the fixture. The most common means of this is a factory installed plate on the water heater. Incorrect answer. Please choose another answer.

29.	Vacuum breakers are to be installed in conjunction with the inlet piping that serves a water heater.
		True
		False
Water heaters must be protected from back siphonage. This is done with the installation of a vacuum breaker in the inlet piping that supplies the water heater with cold water. Normally a tee fitting is installed in the inlet riser. A short section of pipe extends horizontally and then turns 90 degrees to a vertical position where it extends six inches. A female adapter is installed on the riser and the vacuum breaker is screwed into the female adapter. Incorrect answer. Please choose another answer.

30.	The installation of an electric water heater requires which of the following to be in close proximity to the fixture?
		a. An ABC-type fire extinguisher
		b. An electrical disconnect switch that is dedicated to only the water heater
		c. A ventilation fan
		d. A minimum of two light sources to allow for service work to be completed
		e. Both a and b
A dedicated electrical disconnect switch is required to be installed in close proximity to any electric water heater. Gas-fired and oil-fired water heaters require the installation of approved cutoff valves installed on the fuel piping in close proximity to the water heater. Incorrect answer. Please choose another answer.

Recycling Gray Water

31.	Fifteen-pound roofing felt is the preferred cover material for aggregate installed in a seepage pit or trench.
		True
		False
Aggregate in a seepage pit is required to be covered. Approved covering is required to be constructed of approved synthetic materials. Roofing felt is not an approved cover material. An acceptable option is the use of nine inches of uncompacted marsh hay or straw. Incorrect answer. Please choose another answer.

32.	All gray water reservoirs are required to be fitted with a drain at the lowest point of the reservoir. This drain is required to discharge to _____________.
		a. a catch basin
		b. a gravel bed for dissipation into approved soil
		c. a sanitary drainage system
		d. Any of the above
Drains for gray water collection reservoirs are required to discharge into sanitary drainage systems. The drain must originate at the lowest point of the collection reservoir. The size of the drain pipe must be equal to, or larger than, the influent pipe for the reservoir. All collection reservoirs are required to be able to be drained if needed. Incorrect answer. Please choose another answer.

33.	To avoid confusing gray water with potable water you must dye gray water. What color dye are you required to use to identify water as gray water?
		a. Blue or green
		b. Green or yellow
		c. Red or blue
		d. Orange or green
Gray water is to be dyed either blue or green before it can be used in a plumbing system. Blue and green are the only acceptable colors allowed for the identification of gray water. This is an important part of the plumbing code that many plumbers are not aware of unless they work with recycling gray water on a regular basis. Incorrect answer. Please choose another answer.

Storm Drainage

34.	Storm-water drainage systems have the same requirements for cleanouts as sanitary drainage systems.
		True
		False
It is true that the same cleanout rules and regulations that apply to a sanitary drainage system apply to storm-water drainage systems. Incorrect answer. Please choose another answer.

35.	Which of the following types of valves are likely to be found in a storm-drainage system?
		a. Stop valves
		b. Flapper valves
		c. Backwater valves
		d. Stop-and-waste valves
Backwater valves are used in storm-drainage systems. Any backwater valve used in such a system must be of an approved type for the intended use. These valves prevent drainage water from backing up into a system beyond the point of the backwater valve. Incorrect answer. Please choose another answer.

36.	Assume that you are drawing a piping diagram for the installation of a sump pump. Which of the following are you going to show installed in the discharge piping?
		a. Check valve
		b. Stop valve
		c. Backwater valve
		d. Butterfly valve
Sump pumps should be equipped with check valves in their discharge piping. This prevents water that has been pumped up from running down the drainage piping and refilling the sump. If this happens, the pump will have to pump the water again. This puts undue use on the pump. The check valve prevents water from running back into the sump. When a check valve is in place it can extend the life of a sump pump considerably. Incorrect answer. Please choose another answer.

Fuel Gas

37.	What is the maximum allowable pressure for plastic gas piping that conveys natural gas?
		a. 60 psig
		b. 80 psig
		c. 100 psig
		d. 125 psig
The maximum allowable pressure for plastic gas piping that conveys natural gas is 100 psig. Incorrect answer. Please choose another answer.

38.	Unions installed on gas piping are required to ______________.
		a. be dielectric unions
		b. have a minimum diameter of 0.5 inches
		c. be tested bi-annually for leaks
		d. be visible
Unions installed on gas piping must be visible. The fact that unions are intended to allow easy disconnection at the point where they are installed requires that they must be visible and available for testing. Incorrect answer. Please choose another answer.

39.	The maximum allowable pressure to be used when testing gas piping is ________.
		a. 38 psig
		b. 42 psig
		c. 100 psig
		d. 125 psig
Gas piping cannot be tested with a pressure that is in excess of 125 psig. The code requires test pressures to be less than 1.5 times the proposed maximum working pressure. The minimal allowable test pressure is 3 psig. Incorrect answer. Please choose another answer.

Quality starts with who wrote the material.

Our practice exam writer

Dodge Woodson

was a master plumber and gas fitter for over 30 years. He built his own plumbing business and has trained countless plumbers. In addition to being a field plumber and contractor, Woodson served as adjunct faculty at Central Maine Technical College where he taught both plumbing licensing preparation courses and plumbing apprenticeship courses. As R. Dodge Woodson, he is a best-selling author and is the most prolific plumbing author in print with McGraw-Hill. He is often referred to as America’s Plumber.

Charles Redecker

is a master plumber instructor and education director with the National Center for Construction Education and Research. Charles has taught plumbing with the NCCER for over 10 years. Prior to working with the NCCER, Charles taught plumbing at the Rankin Technical College. Charles has owned and run various plumbing businesses since 1979 in St. Louis, Missouri.

Terry Lunt

is a plumbing and master craft instructor with Associated Builders and Contractors in Southern California. He has also been a core curriculum instructor and subject matter expert in plumbing with the National Center for Construction Education and Research. Terry has worked in the plumbing industry for over 30 years.

Joseph Cromwell

is a master plumber in Illinois and Indiana. He was a continuing educaiton instructor and apprentice instructor for over twenty years with the United Association of Plumbers and Pipefitters.

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