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Exam Review

Key Facts: WA Plumber Exam

70%

Passing score on each portion

PSI bulletin

150

Exam items (100 + 25 + 25)

PSI bulletin

270 min

Total time (3 × 90 minutes)

PSI bulletin

UPC 2015

Code basis with WA amendments

WA L&I

The Washington journey level plumber exam has 150 items in three closed-book, 90-minute portions (100 code, 25 waste and vent drawing, 25 water sizing drawing), each requiring 70%. L&I bases it on the 2015 UPC with Washington amendments and provides Tables 702.1, 610.3, 610.4, and 610.10, but not Table 703.2.

Sample WA Plumber Practice Questions

Try these sample questions to review concepts for the WA Plumber exam. Each question includes a detailed explanation. Start the interactive quiz above for the full 298+ question experience with AI tutoring.

1Which agency oversees plumber licensing in Washington State?
A.Washington Department of Commerce
B.Washington Department of Labor & Industries (L&I)
C.Washington State Department of Health
D.Washington Department of Licensing
Explanation: The Washington Department of Labor & Industries (L&I) oversees plumber licensing in the state. L&I administers the plumbing program, issues licenses, and enforces the state plumbing code.
2Washington State's plumbing code is based on which model code?
A.International Plumbing Code (IPC)
B.National Standard Plumbing Code (NSPC)
C.Uniform Plumbing Code (UPC) 2015 with Washington amendments
D.Uniform Plumbing Code (UPC) 2024
Explanation: Washington State uses the Uniform Plumbing Code (UPC) 2015 edition with Washington State amendments as the basis for its plumbing regulations. The UPC is published by IAPMO and adopted by many western states.
3What is the passing score required on the Washington journeyman plumber exam?
A.60%
B.65%
C.70%
D.75%
Explanation: Washington requires a 70% passing score on the journeyman plumber exam administered through PSI. The exam consists of approximately 100 multiple-choice questions with a 3-hour time limit.
4Per the UPC, what is the minimum slope for a 4-inch horizontal drainage pipe?
A.1/16 inch per foot
B.1/8 inch per foot
C.1/4 inch per foot
D.1/2 inch per foot
Explanation: Per the UPC, horizontal drainage pipes 3 inches and larger require a minimum slope of 1/8 inch per foot (approximately 1% grade). This ensures adequate flow velocity for waste transport while maintaining reasonable vertical drops.
5Per the UPC, what is the DFU (Drainage Fixture Unit) value for a water closet (flush tank type)?
A.2 DFU
B.3 DFU
C.4 DFU
D.6 DFU
Explanation: Per the UPC, a water closet with a flush tank (gravity tank) has a DFU value of 4. This is the same value used for sizing drainage and vent piping. Flush valve (flushometer) water closets may have different DFU values.
6Per the UPC, what is the minimum building sewer size?
A.3 inches
B.4 inches
C.6 inches
D.Depends on DFU load only
Explanation: Per the UPC, the minimum building sewer size is 4 inches. This differs from the IPC which allows 3-inch building sewers. The UPC 4-inch minimum provides greater capacity and reduces the risk of blockages.
7Per the UPC, what is the maximum distance between cleanouts in a horizontal drainage line?
A.50 feet
B.75 feet
C.100 feet
D.150 feet
Explanation: Per the UPC, cleanouts must be installed at intervals not exceeding 100 feet in horizontal drainage lines. Additional cleanouts are required at each aggregate change of direction exceeding 135 degrees.
8Per the UPC, what is the minimum trap seal depth?
A.1 inch
B.2 inches
C.3 inches
D.4 inches
Explanation: The UPC requires a minimum trap seal depth of 2 inches for most fixtures. The maximum trap seal is 4 inches. The water seal in the trap prevents sewer gases from entering the building.
9Per the UPC, what is the maximum number of fixture units allowed on a 2-inch horizontal branch?
A.3 DFU
B.6 DFU
C.12 DFU
D.16 DFU
Explanation: Per the UPC fixture unit tables, a 2-inch horizontal branch drain can serve a maximum of 6 DFUs. This limit ensures the pipe has adequate capacity for the fixtures connected to it.
10Per the UPC, what type of fitting is required for a horizontal change of direction in a drainage system?
A.Any standard elbow
B.Long-sweep fittings or combination of fittings with equivalent sweep
C.Short-radius elbows
D.Sanitary tee only
Explanation: The UPC requires long-sweep fittings or a combination of fittings with an equivalent sweep for horizontal changes of direction in drainage systems. Long-sweep fittings maintain proper flow patterns and reduce the risk of blockages.

About the WA Plumber Exam

Washington journey level (PL01) plumber exam administered by PSI for L&I. It has three closed-book portions: 100 code and trade-knowledge questions from UPC Chapters 1-10, 15, 16, and 17 with Washington amendments, a 25-item waste and vent sizing drawing, and a 25-item water sizing drawing. L&I bases the exam on the 2015 UPC with Washington amendments.

Exam sponsor: Washington Department of Labor & Industries (L&I). The requirements and fees below concern the certification or admission exam, separate from our free practice resources.

Questions

150 questions

Time Limit

270 minutes (three 90-minute portions)

Passing Score

70% on each portion

Exam / Certification Fees

$202.10 L&I application + $84 PSI exam fee

Exam sponsor website

Reported exam pass rate: Not published. Exam sponsor website

Fees, eligibility, and exam policies can change. Confirm them with the exam sponsor before applying or paying.

Our practice resources: topics covered

We aim to reflect publicly available exam outlines and topic information in our study resources. Coverage, format, and difficulty may differ from the actual exam, and we cannot guarantee that every detail is accurate or current. Confirm exam requirements, fees, and policies with the official exam sponsor.

66.7%

Journey level code and general trade knowledge

100 items from UPC Chapters 1-10, 15, 16, and 17 with Washington amendments (WAC 51-56), closed book

16.7%

Waste and vent journey level drawings

25 items: size fixture units and minimum drain and vent pipe sizes on a building drawing from UPC Chapter 7 while maintaining aggregate venting; Table 703.2 is not provided

16.7%

Water sizing journey level drawings

25 items: size hot and cold water piping on a building drawing from UPC Chapter 6 using Tables 610.3, 610.4, and 610.10

Preparing for the WA Plumber Exam

What You Need to Know

  • Passing score: 70% on each portion
  • Exam length: 150 questions
  • Time limit: 270 minutes (three 90-minute portions)
  • Exam / certification fees: $202.10 L&I application + $84 PSI exam fee Official sources

Using Our Practice Resources

  • Work through all 298 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

WA Plumber: Suggested Study Strategy

1Study the 2015 UPC with Washington amendments (WAC 51-56); L&I bases the exam on that edition
2Memorize Table 703.2 with its notes, because it is not provided on the exam
3Know Washington amendments such as 21-inch dwelling-unit toilet clearance, 900-square-inch showers, and 12- or 18-inch cleanout clearance
4Practice Part 3 water sizing with Tables 610.3, 610.4, and 610.10, using 1/2 psi per foot of elevation
5Practice Part 2 drawings, including the aggregate venting check required by UPC 904.1
6Remember that Washington does not adopt UPC Chapter 12 fuel gas, building sewer sections, or Table 422.1
7Review backflow device selection, including Washington rules for boilers and carbonators
8Budget about 54 seconds per code question and 3.6 minutes per drawing question

Frequently Asked Questions

How is the Washington journeyman plumber exam structured?

PSI gives the journey level exam in three closed-book portions: 100 code and general trade knowledge items, 25 waste and vent drawing items, and 25 water sizing drawing items. Each portion is 90 minutes and requires 70%, and candidates must pass all three.

Which plumbing code is the Washington plumber exam based on?

L&I states that the Washington plumber examinations are based on the 2015 Uniform Plumbing Code with amendments adopted by the State Building Code Council in chapter 51-56 WAC. The current field code adopts the 2021 UPC, effective March 15, 2024.

How much does the Washington journeyman plumber exam cost?

L&I charges a $202.10 non-refundable exam application fee, PSI charges $84 for the three-portion exam, and the journey level certificate costs $242.70 for three years, for $528.80 in fees before study materials.

Which tables are provided on the Washington journey level exam?

L&I provides UPC Tables 702.1, 610.3, 610.4, and 610.10 with the closed-book journey level exam. Table 703.2, which sets drain and vent sizes, is not provided and must be memorized.