How to Become a Licensed Plumber in Washington State

Dreaming of a stable, hands-on career with strong earning potential? Plumbing might be your perfect fit—and in Washington State, becoming a licensed plumber opens doors to steady work, entrepreneurial freedom, and community trust. But the path isn’t always clear. How to become a licensed plumber in Washington State involves specific education, hands-on training, and state exams. This guide breaks it all down—so you can turn your ambition into a licensed profession, one pipe at a time.

What Are the Basic Requirements to Become a Plumber in Washington?

Before you pick up your first wrench, know this: Washington doesn’t issue a “journeyman” license like many states. Instead, it offers two main plumbing credentials through the Washington State Department of Labor & Industries (L&I):

1. Plumbing Specialty Certificate (for apprentices and trainees)
2. Plumbing Contractor License (for those running their own business)

To work legally on plumbing systems in Washington, you must be either:

• A registered plumbing trainee under a certified plumber, or
• A certified journey-level plumber, or
• A plumbing contractor with proper licensing.

💡 Key Fact: As of 2025, Washington requires 8,000 hours (about 4 years) of supervised work experience to qualify for the journey-level plumber exam.

Step-by-Step Guide: How to Become a Licensed Plumber in Washington State

Follow these five clear steps to earn your plumbing credentials in Washington:

1. Meet the Minimum Eligibility Criteria

• Be at least 16 years old (to register as a trainee).
• Have a high school diploma or GED (recommended, though not always mandatory for trainee registration).
• Be legally authorized to work in the U.S.

2. Register as a Plumbing Trainee with L&I

You must register with the Washington State Department of Labor & Industries before starting any plumbing work—even as an apprentice.

• Cost: $52 (as of 2025)
• Renewal: Every 2 years
• Requirement: Work only under the direct supervision of a certified journey-level plumber or contractor.

📌 Tip: Keep detailed logs of your hours. L&I may audit your experience records.

3. Complete 8,000 Hours of Supervised Work Experience

This is the core of your training. Over 4 years, you’ll:

• Install, repair, and maintain pipes, fixtures, and drainage systems
• Learn local and state plumbing codes (based on the Uniform Plumbing Code)
• Gain experience in residential, commercial, and possibly industrial settings

You must document at least 8,000 hours of hands-on work. Of these:

• 4,000 hours must be in residential or commercial plumbing
• No more than 2,000 hours can be in maintenance-only roles

4. Complete Required Classroom Instruction

In addition to field hours, Washington requires 96 hours of plumbing-related classroom training, including:

• 48 hours of basic plumbing theory
• 24 hours of code training (Uniform Plumbing Code)
• 24 hours of industry-related instruction (e.g., safety, blueprint reading)

Many apprentices fulfill this through state-approved programs like those at Bates Technical College (Tacoma) or Lake Washington Institute of Technology.

🔗 For more on plumbing education standards, see the Uniform Plumbing Code overview on Wikipedia .

5. Pass the Washington Journey-Level Plumber Exam

Once you’ve completed your hours and training, apply to take the exam through L&I.

• Exam fee: $125
• Format: 100 multiple-choice questions
• Passing score: 70%
• Topics: Plumbing codes, system design, venting, drainage, water supply, and safety

You’ll receive your Journey-Level Plumber Certificate within 2–3 weeks of passing.

✅ Pro Tip: Use L&I’s official study guide and take practice tests. The exam is open-book—but only with approved code materials.

How Much Does It Cost to Get Licensed?

Note: Many employers cover training and exam costs for apprentices.

Should You Become a Plumbing Contractor?

Once certified, you can work independently—but to pull permits or run a business, you need a Plumbing Contractor License.

Requirements:

• Hold a valid journey-level plumber certificate
• Pass a business & law exam ($125 fee)
• Carry general liability insurance ($200,000 minimum)
• Register your business with the Washington Secretary of State

💼 Stat: The U.S. Bureau of Labor Statistics reports plumbers in Washington earn a median salary of $68,500/year, with top earners exceeding $95,000—especially in Seattle and Bellevue.

Common Challenges (and How to Overcome Them)

FAQ: How to Become a Licensed Plumber in Washington State

Q1: Can I transfer my plumbing license from another state to Washington?

A: Washington does not have formal reciprocity with other states. However, if you’re licensed elsewhere, you may qualify for experience credit. Submit your credentials to L&I for review—they’ll determine if you meet Washington’s 8,000-hour standard.

Q2: How long does it take to become a licensed plumber in WA?

A: Typically 4 years as a registered trainee, plus time for classroom training and exam prep. Some complete it in 3.5 years with full-time work; others take longer if working part-time.

Q3: Do I need a college degree to be a plumber in Washington?

A: No. A high school diploma or GED is sufficient. Most training happens on the job and through technical colleges.

Q4: Can I work as a plumber without a license in Washington?

A: Only as a registered trainee under direct supervision. Performing plumbing work without proper registration or certification is a Class B misdemeanor—fines up to $5,000 and legal penalties.

Q5: Are plumbing jobs in demand in Washington?

A: Yes. The Washington State Employment Security Department projects 12% growth in plumbing jobs through 2030—faster than average—due to new construction, aging infrastructure, and green building initiatives.

Q6: What’s the difference between a certified plumber and a contractor?

A: A certified journey-level plumber can perform plumbing work but cannot run a business or pull permits. A plumbing contractor can do all that—and hire employees—once licensed by L&I.

Final Thoughts: Your Future Starts with One Pipe

Becoming a licensed plumber in Washington State is a smart career move—offering job security, competitive pay, and the pride of mastering a vital trade. While the path requires dedication, every hour you log brings you closer to independence and expertise.

If you’re ready to turn wrenches into wages, start by registering as a trainee today. And if this guide helped you, share it with someone else dreaming of a hands-on career—on Facebook, LinkedIn, or your local trade school forum. The next generation of Washington plumbers is being built now. Will you be part of it?

🛠️ Remember: In plumbing—as in life—pressure creates flow. Keep pushing forward.