Thinking about launching your own plumbing business in Washington? You’re not alone—thousands of skilled tradespeople aim to turn their expertise into licensed careers each year. But before you can legally offer plumbing services for pay in the Evergreen State, you must obtain a plumbing contractors license. In this guide, we’ll walk you through exactly how to get a plumbing contractors license in Washington State—clearly, accurately, and without the confusing jargon.
What Is a Plumbing Contractors License in Washington State?
In Washington, any individual or business that installs, repairs, or alters plumbing systems for compensation must hold a valid plumbing contractor license issued by the Washington State Department of Labor & Industries (L&I). This isn’t optional—it’s required by law under RCW 18.104.030.
Without this license, you risk fines up to $5,000 per violation, legal action, and being barred from future licensing. More importantly, clients won’t trust unlicensed plumbers—especially when insurance, warranties, and building code compliance are on the line.
💡 Did You Know? Over 12,000 active plumbing contractor licenses are currently issued in Washington (L&I, 2025). Competition is healthy—but only licensed pros can play.
Who Needs a Plumbing Contractor License in WA?
You need this license if you:
- Perform plumbing work for pay (even small jobs like fixing a leaky faucet).
- Own a plumbing business (sole proprietorship, LLC, or corporation).
- Supervise plumbing projects as a general contractor (if plumbing is part of the scope).
Exception: Homeowners doing plumbing work on their own primary residence don’t need a license—but they still must pass inspections.
Step-by-Step: How to Get a Plumbing Contractors License in Washington State
Follow these 6 verified steps to become a licensed plumbing contractor in WA:
Step 1: Meet the Basic Eligibility Requirements
Before applying, ensure you meet all of the following:
- Be at least 18 years old.
- Have a U.S. Social Security Number or ITIN.
- Possess 4 years (8,000 hours) of full-time journey-level plumbing experience within the last 10 years.
- At least 2,000 hours must be in residential or commercial plumbing (not just maintenance).
- Have no disqualifying criminal history (L&I conducts background checks).
📌 Tip: Your experience must be verified by a licensed plumber, contractor, or employer using L&I’s Affidavit of Experience form.
Step 2: Complete Required Education (If Applicable)
While Washington doesn’t mandate formal classroom training, many applicants take prep courses to pass the exam. Recommended topics include:
- Washington State plumbing code (based on UPC – Uniform Plumbing Code)
- Business & law regulations
- Plan reading and isometric drawings
Free resources are available via L&I’s contractor education portal.
Step 3: Pass the Washington Plumbing Contractor Exam
The exam has two parts:
| Section | Format | Passing Score | Time Allowed |
|---|---|---|---|
| Trade Knowledge | 100 multiple-choice | 70% | 4 hours |
| Business & Law | 50 multiple-choice | 70% | 2 hours |
- Administered by PSI Services at testing centers in Seattle, Spokane, Tacoma, and more.
- Fee: $138 (as of 2026).
- You can retake the exam after 30 days if you fail (max 3 attempts per application cycle).
✅ Pro Tip: Use L&I’s official exam content outline and practice with sample questions. Over 65% of first-time takers pass when they study the state-specific code sections.
Step 4: Obtain a Surety Bond and Liability Insurance
Before your license is issued, you must provide:
- A $6,000 surety bond (protects clients if you violate laws or fail to complete work).
- General liability insurance of at least $200,000 per occurrence.
Both must name the State of Washington, Department of Labor & Industries as the certificate holder.
⚠️ Warning: Never use an expired or invalid bond—L&I verifies every submission. Rejection delays your license by weeks.
Step 5: Submit Your Application to L&I
Complete the Plumbing Contractor License Application online via L&I’s eLicensing system.
Required documents:
- Completed application form
- Affidavits of experience (signed by verifiers)
- Exam score report
- Bond and insurance certificates
- $146 application fee (non-refundable)
Processing time: 7–14 business days if everything is in order.
Step 6: Receive Your License and Renew Annually
Once approved, you’ll get:
- A license number (e.g., PLMB.WA.123456)
- A wall certificate
- Authorization to pull permits and bid on jobs
Renewal: Every year by your expiration date. Cost: $146. Late renewals incur a $50 penalty.
🔁 Good to Know: Licenses expire on the applicant’s birth month anniversary. Set a calendar reminder!
Common Mistakes to Avoid
Even experienced plumbers stumble here:
- Underreporting hours: Only count hands-on plumbing—not HVAC or electrical work.
- Using unverified references: Your verifier must be licensed or a former employer with records.
- Skipping the business section: Many fail the law portion because they focus only on technical skills.
- Assuming reciprocity: Washington does not have license reciprocity with Oregon, Idaho, or California.
For more context on licensing standards across states, see Wikipedia’s overview of U.S. occupational licensing.
Plumbing License vs. Journeyman vs. Apprentice: What’s the Difference?
| Role | Can Work Independently? | Can Pull Permits? | License Required? |
|---|---|---|---|
| Apprentice | ❌ No | ❌ No | Registered with L&I |
| Journeyman Plumber | ✅ Yes (under contractor) | ❌ No | Must pass journeyman exam |
| Plumbing Contractor | ✅ Yes | ✅ Yes | Full contractor license |
Only contractors can legally own a plumbing business and hire others.
FAQ: How to Get a Plumbing Contractors License in Washington State
Q1: How long does it take to get a plumbing contractor license in WA?
A: Typically 4–8 weeks from application to approval—if you already have the experience and pass the exam on your first try. Delays happen due to incomplete affidavits or failed exams.
Q2: Can I get a license with a felony conviction?
A: It depends. L&I reviews criminal history on a case-by-case basis. Crimes involving fraud, theft, or violence may disqualify you. You can request a pre-application review to assess eligibility.
Q3: Do I need a local city license too?
A: Some cities (like Seattle or Bellevue) require additional business licenses, but not separate plumbing certifications. Your state license covers trade work statewide.
Q4: What if I’m already licensed in another state?
A: Washington doesn’t offer reciprocity, but your out-of-state experience can count toward the 8,000-hour requirement if properly documented.
Q5: How much does the entire process cost?
A: Total estimated cost:
- Exam: $138
- Application: $146
- Bond: ~$100–$200/year
- Insurance: ~$500–$1,200/year
Total: $800–$1,700 in the first year.
Q6: Can I operate as an LLC with this license?
A: Yes! You can apply under a business entity (LLC, corporation, etc.). Just designate a qualifying agent—a licensed individual who oversees plumbing work.
Conclusion
Getting a plumbing contractors license in Washington State is a smart, necessary step to build a credible, profitable, and legal business. While the process requires documentation, testing, and upfront costs, it opens doors to higher-paying jobs, client trust, and long-term growth.
Now that you know how to get a plumbing contractors license in Washington State, take action:
✅ Gather your experience records
✅ Schedule your exam
✅ Secure your bond
And if this guide helped you, share it with a fellow tradesperson on Facebook, LinkedIn, or Reddit! The skilled trades community thrives when we lift each other up.
Ready to start? Visit the official WA L&I Plumbing Contractor page today.
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