Septic Solutions Explains Why Some Snohomish County Remodels Need a Septic Inspection Before a Building Permit

Septic Solutions LLC explains why Snohomish County additions, ADUs, and extra bedrooms may need a septic construction clearance before a building permit.

Septic Solutions Explains Why Some Snohomish County Remodels Need a Septic System Inspection Before a Building Permit

Snohomish County homeowners planning additions, ADUs, or an extra bedroom are encouraged to check their septic as-built records before plans are final.

ARLINGTON, Wash., Oct. 8, 2026 — Septic Solutions LLC, a septic installation, inspection, and pumping company serving Island, King, Skagit, Snohomish, and Whatcom counties, is reminding Snohomish County homeowners that a remodel on a property with a septic system may need approval from the Snohomish County Health Department before the building permit is issued. The company says many homeowners learn this only after their plans are drawn, when the permit is ready to be issued but delayed by a septic system check.  

The Health Department calls this approval a construction clearance, which confirms that the project is compatible with the existing or proposed septic system and will not damage it. Outside city limits, applicants submit the clearance form through the Snohomish County Planning & Development Services portal. Inside city limits, the city’s building department decides whether the form is required. Once the Health Department approves the clearance, the building permit can be issued. 

The form asks for the total number of bedrooms before and after construction, so an addition or a major remodel that adds a bedroom changes the number the reviewer sees. The Health Department also counts rooms that could serve as bedrooms, regardless of closets, windows, or doors. An accessory dwelling unit (ADU) raises the same question. When an ADU shares the existing system, state design rules add a minimum of 120 gallons of daily design flow per bedroom for the additional dwelling. The bedroom count is the number that has the most impact on the review. The Health Department says the size of a septic system is based on the number of bedrooms it serves, and it asks homeowners to check the capacity and location on their approved septic application or final as-built. Under WAC 246-272A-0230, a single-family septic system is designed for a minimum of 120 gallons of sewage per bedroom per day, and the local health officer may require a higher flow for larger dwellings. WAC 246-272A-0232 sets the minimum septic tank volume at 1,000 gallons for up to four bedrooms, plus 250 gallons for each additional bedroom.

Location matters as much as capacity. Under WAC 246-272A-0210, the edge of the drainfield and the reserve area must sit at least 10 feet from a building foundation and at least 5 feet from a property or easement line, while the septic tank must stay at least 5 feet from a foundation. The rule also requires a reserve area large enough to treat 100 percent of the design flow, and the drainfield cannot go in an area subject to encroachment by buildings or construction. In practice, an addition or an ADU has to fit on the lot without crowding the drainfield or the reserve area. All three rules are current as of October 2026.

“When someone is planning an addition or an ADU, one of the first questions is whether the property and the existing septic system can support it,” said Art Nikolin, Operations Manager at Septic Solutions LLC. “That is something worth finding out before the project gets too far into design.”

The place to start is the as-built record. The Health Department keeps records for Snohomish County septic systems in its OnlineRME database, and the company says an as-built shows where the tank and drainfield sit, measured from fixed reference points on the property. 

“The records can tell you a lot about the system, but you still have to know how to read them,” Nikolin said. “For most homeowners, looking at an as-built is a lot like looking at a set of construction drawings. The information is there, but it may not be obvious what it means for the property.”

Homeowners can search the database themselves. Septic Solutions also runs the search at no charge, emails the documents, usually within one business day, and follows up with a call to explain what they mean for the property. The company describes the process in its updated guide to septic records in Snohomish County.

A septic review does not automatically mean the system has to be replaced. A licensed septic designer or engineer can compare the existing system with the planned bedroom count, and the outcome depends on what the records and the site show. Some properties can support the planned addition with the existing system. Others may need the septic design changed, the existing system expanded, or additional capacity added before the project can move forward. When a system does need work, a licensed designer prepares the design, the Health Department reviews it, and the finished installation is inspected before it is approved. Septic Solutions handles installation for homeowners in that situation.

“A review does not automatically mean somebody needs a new septic system,” Nikolin said. “The first step is to understand what is already there, what the homeowner wants to add, and whether the existing system and site can support it.”

Homeowners with questions about the clearance process can contact the Snohomish County Health Department’s Environmental Health Division at 425-339-5250 or SHD-EHQ@snoco.org.

About Septic Solutions LLC

Septic Solutions LLC provides septic pumping, inspections, installation, repair, maintenance, drainfield service, and 24/7 emergency response across King, Snohomish, Skagit, Island, and Whatcom counties. The company is based in Arlington and lists additional contact locations in Mill Creek, Redmond, and Mount Vernon. Septic Solutions advertises same-day septic pumping, free estimates, and extended workmanship and installation warranties. Homeowners can request an estimate through septicsolutionsllc.com.

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Company: Septic Solutions LLC
Contact Person: Art Nikolin
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Website: septicsolutionsllc.com
Phone: (360) 322-4639
Title: Septic Solutions LLC