Licensing Guides
Washington Septic License: How to Become a Septic Contractor in Washington
Septic, WA
October 1st, 2026
Table of Contents
What Is the Mean Wage for a Septic Professional in Washington?
How Much Does It Cost to Get a Septic License in Washington?
How Long Does it Take to Get a Septic License in Washington?
How Can I Prepare for the Septic License Exam in Washington?
What Are the Penalties for Unlicensed Septic Work in Washington?
Septic License Requirements in Washington
We all need safe, reliable sewage management for our homes and businesses. Those homeowners and businesses that rely on septic tanks, also known as on-site septic systems (OSS), depend on people who know how to install and maintain those systems while protecting public health.
The Washington State Department of Ecology reports about one-third of Washington households rely on septic systems.
According to the Bureau of Labor Statistics (BLS), there are 30,650 septic tank servicers and sewer pipe cleaners nationwide, and Washington employs about 1,600 of them. Employment is projected to grow 8% from 2024 to 2034 across the country, with about 2,900 job openings for these skilled workers each year. In Washington, that growth rate is expected to be even higher — projected at 11% from 2022 to 2032 — according to CareerOneStop, the U.S. Department of Labor’s job search website.
If you’re thinking about starting a septic business or working in this field, you need to know the requirements in your state or local jurisdiction. This guide will help you determine what you need before you get started in Washington.
In Washington State, the Washington State Department of Licensing issues licenses for On-Site Wastewater Treatment System Designers. Professional engineers can design systems without obtaining this license.
Local health departments or environmental health divisions handle certifications and septic permit applications for septic system installers, pumpers, and maintenance service providers.
Types of Septic Licenses in Washington
The statewide septic license in Washington is the On-Site Wastewater Treatment System Designer, which allows you to design systems for new installations, alterations, and repairs.
There are also local requirements for septic system professionals enforced through public health and environmental health services departments. For example, King County certifies Installers, Maintainers, and septic tank Pumpers/Haulers.
Steps to Get a Septic License in Washington
To obtain an On-Site Wastewater Treatment System Designer license, follow these steps:
Meet application requirements: Possess a high school diploma or its equivalent and four years of experience showing increased responsibility as defined in WAC 196-32-020.
Submit your application, a completed Washington On-Site Wastewater Designer/Inspector Law Review, and your experience verification.
Pay $200 fee.
Pass the exam with a score of 80% or higher.
To become an Associate/Master Installer in King County, follow these steps:
Complete a health officer-recognized course in the basics of septic systems and installation.
For Associate: Provide proof that you are working under a Master Installer.
Apply for the exam. The Associate exam incurs a $220 fee, and the Master exam incurs a $352 fee.
Master applicants must obtain bond and general liability insurance.
Submit certification application with the required fee.
The Liquid Waste Pumper/Hauler and On-Site System Maintainer certification process in King County is relatively the same, with variations for experience requirements and fees.
Benefits of Getting a Septic License in Washington
Earning your Washington septic credential opens doors, whether you design systems statewide or install and maintain them for a local health jurisdiction. The benefits include:
It is required by law. Washington makes it unlawful to design on-site wastewater treatment systems without a license, so licensure is your legal foundation to work.
Your license is proof of your skill and experience.
Licensed professionals can operate and advertise a business, pull permits, and pass inspections.
A credential makes you eligible to bid on public and government projects.
Licensure protects both your business and your customers.
It gives you a competitive advantage and increases your earning potential.
What Is the Mean Wage for a Septic Professional in Washington?
The annual mean wage for septic tank servicers and sewer pipe cleaners nationwide is $53,500, according to the U.S. Bureau of Labor Statistics. Washington pay runs higher than the national average. The median annual wage in Washington is $63,090.
As you gain experience, your pay tends to climb. Based on the same BLS Occupational Employment and Wage Statistics May 2025 estimates cited above, wages by percentile in Washington look like this:
Entry level (10th percentile): $46,690
25th percentile: $56,770
Median (50th percentile): $63,090
75th percentile: $75,670
Experienced (90th percentile): $83,830
The terms “mean wage” and “median salary” can be confusing. Here is the difference:
Mean wage tells you the mathematical average of all salaries.
Median salary tells you the point at which half of workers earn less and half earn more, and it is usually a better indicator of what most people actually make.
Salaries vary widely depending on where you work in Washington and factors like experience, certifications, and whether you own the business. Designers who carry a statewide license and take on complex system work generally earn more than entry-level installers.
How Much Does It Cost to Get a Septic License in Washington?
There’s a $200 fee to obtain the On-Site Wastewater Treatment System Designer license.
The King County certifications cost:
Associate Installer: $220 exam fee and $129 certificate fee
Master Installer: $352 exam fee and $176 to $352 certificate fee depending on when you apply
Liquid Waste Pumper/Hauler: $215 exam fee, certificate fee of $304 for business owner or $133 for employee, and $122 per vehicle
On-Site System Maintainer: $352 exam fee and $176 to $352 certificate fee depending on when you apply
King County publishes current fees on its on-site sewage certifications page.
What Business Owners Need to Know
Getting the most out of a septic installation technician, no matter where they are in their licensing journey, takes work. ServiceTitan cloud-based, all-in-one septic business software gives technicians and business owners the technology they need to do the work efficiently, and the data they need to do it smartly.
SMS communications that keep customers informed about the technician’s visit.
Location-specific service history, including recorded calls, accessible from the mobile app.
Required forms that ensure every job is done right, driving consistency.
The ability to build multi-option proposals with photos, on-site, in minutes.
Sales presentations that make conversations with customers easier and drive the average ticket.
Mobile payment acceptance, eliminating lost checks and increasing cash flow.
To learn more, schedule a demo with a product expert today.
How Long Does it Take to Get a Septic License in Washington?
Septic system designers need four years of experience to obtain licensure. In King County, you need two years of experience to become an On-Site System Maintainer. Other King County certifications require a training course and exam.
Washington Septic Training Programs and Schools
King County requires certificate applicants to take a course offered through one of the following providers:
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Washington Septic Licensing Exam Details
Exams are required for the state Designer license, as well as the King County certifications. Other counties may require exams as well. It’s important to verify licensing requirements in each locality.
Exams cover types of systems, drainfields, proper land use, and more.
How Can I Prepare for the Septic License Exam in Washington?
The statewide On-Site Wastewater Treatment System Designer exam is a multiple-choice, four-hour, open-book exam offered twice a year in both Western and Eastern Washington. Because it is open book, preparation is about organizing your references, not memorizing everything.
Bring bound reference materials only. The board requires references to be bound, such as in a three-ring binder, and does not allow loose-leaf paper.
Use a calculator that follows the NCEES Calculator Policy.
Study system types, drainfields, soil and site evaluation, and proper land use, which are the core subjects the exam covers.
Complete the Washington On-Site Wastewater Designer/Inspector Law Review, which requires a passing score of 80%. The board sets the passing standard for the main designer exam and reviews all results for final approval.
For local King County certifications, exams are offered on a set schedule through the county and its partner organizations, so review the health-officer-recognized course materials before you test.
Do I Need to Renew My Washington Septic License?
Yes, On-Site Wastewater Treatment System Designer licenses must be renewed every two years for a $128 fee. King County certificates expire on Dec. 31 each year. The renewal fee is $129 for Associate Installer, $352 for Master Installer, $305 for Liquid Waste Pumper/Hauler business owner or $133 for employee, and $352 for On-Site System Maintainers.
Does My Washington Septic License Work in Any Other State?
No. A Washington On-Site Wastewater Treatment System Designer license does not automatically transfer to another state. If you plan to work elsewhere, you will need to apply under that state’s rules and, in most cases, take that state’s exam. Some states may accept your Washington license or experience as proof of eligibility to test, so check directly with the licensing authority in the state where you want to work.
Does Washington Reciprocate Septic Licenses?
No, Washington does not have reciprocity agreements for septic professionals.
National Septic Certifications
Other certifications can help you demonstrate your proficiency to potential employers and clients. The National Association of Wastewater Technicians and The National Onsite Wastewater Recycling Association offer certifications. Those and other professional certifications are not required but can add to your marketability and therefore increase your opportunity to make more money.
Other Requirements Unique to Washington
Washington splits septic work between a statewide license and local certifications, so where you work changes what you need.
Installer, maintainer, and pumper certifications are local. Under WAC 246-272A-0340, these professionals must obtain approval from the local health officer before providing services in that jurisdiction. King County and Thurston County, for example, each run their own certification programs.
If you run an installation business, you generally must register as a contractor with the Washington State Department of Labor & Industries. Specialty contractors must post a $15,000 bond and carry liability insurance.
The statewide designer license is issued by the Board of Registration for Professional Engineers and Land Surveyors (BRPELS), while professional engineers may design systems without this specific license.
Are There Septic Scholarships in Washington?
Washington does not offer a scholarship dedicated solely to septic professionals, but several state programs can help pay for the training and apprenticeships that lead into the trade.
The Washington Opportunity Grant helps students with incomes at or below 200% of the federal poverty level pay for up to 45 credits of tuition and fees, plus up to $1,000 for books and supplies, in high-demand career programs at community and technical colleges. Your college’s Opportunity Grant coordinator confirms which programs qualify.
The Washington Grant for Apprenticeship provides up to $2,548 for the 2026-27 year to income-eligible residents in registered apprenticeship programs, and the funds do not need to be repaid when requirements are met.
The Washington On-site Sewage System Association (WOSSA) offers scholarships for people entering the trade. Contact WOSSA directly for current award details and deadlines.
How Can Someone Verify My Septic License in Washington?
Clients, employers, and inspectors can confirm your credential through the Washington State Department of Licensing’s official lookup tool.
Go to the Department of Licensing license lookup tool.
Search by name, license number, license type, or location.
Review the results, which show whether a license has been issued, whether it is currently active, and its expiration date.
Local installer, maintainer, and pumper certifications are verified through the county health department that issued them.
When Can a Septic License Get Suspended in Washington?
A suspension temporarily bars a license holder from practicing legally. Washington’s Uniform Regulation of Business and Professions Act and RCW 18.210 set out grounds for discipline, which can include:
Fraud, dishonesty, or acts of moral turpitude related to the practice.
Incompetence, negligence, or malpractice that causes harm.
Being willfully untruthful or deceptive in a design, report, or as-built record.
Submitting false or fraudulent information on a license application.
Aiding unlicensed practice or practicing on an expired, suspended, or revoked license.
A criminal conviction relating to the profession.
Depending on the case, the board can impose sanctions ranging from a reprimand or probation to suspension or revocation, along with civil fines up to $5,000 per violation. The board must also immediately suspend the license of anyone certified as not in compliance with a child support order.
Note: The information above should not be considered legal advice. For detailed and specific rules, refer to RCW 18.210 and WAC 196-32.
What Are the Penalties for Unlicensed Septic Work in Washington?
Designing on-site wastewater treatment systems in Washington without a license is illegal. Under RCW 18.210.160, performing this work without a license, claiming to be qualified without a license, or using a revoked, suspended, or fraudulent license is a gross misdemeanor.
On top of criminal charges, the state can pursue civil enforcement under RCW 18.235.150, including a permanent cease-and-desist order, a civil fine of up to $1,000 for each day of unlicensed activity, and a court injunction to stop the work. Civil remedies do not replace criminal prosecution; both can apply.
Note: The information above should not be considered legal advice. For a detailed explanation, refer to RCW 18.210 and RCW 18.235.
Continuing Education
Licensed Designers must complete 30 hours of continuing education every renewal cycle. King County licensed professional Installers and Maintenance Providers must complete eight continuing education hours every year.
Resources
You can stay up to date on all septic industry news several ways:
Check top septic blogs, including ServiceTitan’s blog.
Read about the latest industry trends, and discover ideas on how to grow your septic business.
Listen to top septic podcasts like ServiceTitan’s “Toolbox for the Trades” podcast.
The Washington State Department of Health offers videos on sewage disposal system basics, septic system inspection, and more.
The states have licensing requirements for other trades, too. You can find out more about how to get an HVAC, plumbing, electrical, or general contractor license in Washington, or in any of the other 49 states and the District of Columbia through the ServiceTitan Licensing Hub.
