Septic System Design in King County

Septic System Design Experts in King & Snohomish County

We are a Washington State licensed septic system design company and pride ourselves on providing timely and cost-effective services for over 35 years to individuals living in King County and Snohomish County.

Ask about our Veteran & Senior Citizen Discounts.

Licensed, Bonded & Insured

Failed septic system? Emergency repairs needed?

*Have a failed system and need a repair, text 911 to 425-248-1140 with the address and we will get back to you within 24hrs

Helpful Resources

Clean Water Loans

Loans to replace failing septic systems in Washington.

Learn More / Apply for Loan

Core Expertise

Veteran & Senior Discounts

At Davis Septic Design, we proudly honor our veterans and the sacrifices they’ve made to protect our country. As a token of our appreciation, we offer exclusive discounts to military veterans on septic repairs. We also extend special savings to senior citizens because we believe in supporting those who have given so much to our community. If your septic system is failing or in need of repair, don’t wait! Give us a call today for your 5% discount, and let our experienced team help you find the best solution. We’re here to ensure your home stays safe and functional—with service you can trust and savings that make a difference.

Services We Provide

*Septic Feasibility / Perc Test – This involves going out to the site where soil log holes will be dug to assess soil types and depth to ensure they meet the counties requirements for an OSS.

*Septic Repair Design / New Construction – There will be certain documents that will be required by the client to obtain which could include the CAD (Critical Area Designation), water certificate or a sewer certificate that is required by the Health Dept. upon design submittal.

*Fast turnaround – Typically allow a week for the site visit, and a week to prepare the design and submit to the County Health Department. (*for repairs only)

Alternative Septic Solutions

We specialize in advanced treatment systems for challenging sites, including aerobic treatment units and specialized filtration systems designed for optimal performance in Pacific Northwest soils.

UV required or NO UV REQUIRED (system specific)

Counties & Cities Served

King County / Snohomish County Septic Design *Please note that we do not work on Island County or Pierce County*

King County

Cities served including:

Algona, Auburn, Beaux Arts Village, Bellevue, Black Diamond, Bothell, Burien, Carnation, Clyde Hill, Covington, Des Moines, Duvall, Enumclaw, Federal Way, Hunts Point, Issaquah, Kenmore, Kent, Kirkland, Lake Forest Park, Maple Valley, Medina, Mercer Island, Milton, Newcastle, Normandy Park, North Bend, Pacific, Redmond, Renton, Sammamish, SeaTac, Seattle, Shoreline, Skykomish, Snoqualmie, Tukwila, Woodinville, Yarrow Point.

Snohomish County

Cities served including:

Arlington, Bothell, Brier, Darrington, Edmonds, Everett, Gold Bar, Granite Falls, Index, Lake Stevens, Lynnwood, Marysville, Mill Creek, Monroe, Mountlake Terrace, Mukilteo, Snohomish, Stanwood, Sultan, Woodway.

System Installation Time-lapse

"See how we work — watch a full drain field install from start to finish."

Specialized Septic Systems

Here are a few of the variety of septic systems we specialize in designing and providing construction management to the installers.

Conventional Systems

Alternative Systems

(Required when there is a lack of area and/or soils)

If your property is required to have an alternative system, we design the most cost-effective system for long term performance and low-cost maintenance.