Washington County, Oregon septic permits and requirements

Permitting authority

Washington County Environmental Health — Onsite Sewage Program

Washington County Environmental Health Septic — 503-846-8722. Septic applications are submitted through the county Public Permitting and Services Portal.

Oregon county-agent framework

Oregon DEQ states that it may authorize counties as its agents for onsite septic permitting under OAR 340-071-0120. County agents can receive and process applications, issue permits, enforce onsite requirements, and perform required inspections. Property-specific local instructions should be followed because application and land-use procedures vary by county.

County Environmental Health issues household septic permits

Washington County Environmental Health states that it issues septic permits for households not served by public sewer. Permits are required for installation of new onsite systems and for repair or alteration of existing systems, tanks, or drainfields.

Site evaluation and reserve area

Washington County requires a site evaluation to determine whether a property is suitable and what type and size of system can be used. The evaluation considers soil, groundwater, slope, streams, wells, cuts and fills, and parcel size. The county also requires enough suitable area for the initial system and an equal repair area.

Connection to available community sewer

Washington County states that if community sewer is available, the property must connect to sewer service rather than use the normal onsite septic route.

Authorization Notice for changes in use or flow

An Authorization approval may be required when a property change could affect an existing septic system, including adding bedrooms, replacing a dwelling, adding a hardship dwelling connection, or changing a system from residential to commercial use.

Existing-system evaluations and records

The county uses Existing System Evaluations to document system location, component size, and functioning status, including for some older unpermitted systems and certain treatment technologies. Septic as-built records can be requested through the county public-records portal.

Official sources

SepticScope summarizes public-agency information for planning purposes. The permitting agency's current instructions control if they differ from this guide.