• Regulations and Procedures

    On-site sewage and wells

    We regulate and enforce installation of septic systems and wells. View applicable county and state regulations that apply to on-site sewage and wells.

    Local Regulations

    State Code

    On-Site Sewage Procedures

    Procedure or guidance document DateNotes
    Additional Fee ProcedureEffective July 2024Outlines when and what additional fees we require.
    Critical Area ComplianceRevised October 2026Updated contact information for critical area sign-off.
    Density for Accessory Dwelling Unit GuidanceRevised August 2018Updated density requirements for lots connected public water.
    Development Activities for Existing Septic SystemsRevised August 2024Updated O&M inspection requirements.
    Extended Maintenance and Minor Repairs (EMMR) Reportable ActivitiesEffective March 2025Outlines approved EMMR activities that do not require a permit or repair application.
    Guidance for Unpermitted Septic ConnectionsEffective June 2024Describes steps you must take for unpermitted septic connects to obtain an RSS.
    High Winter Water Table ReviewRevised December 2022Updated contact info and fee requirements.
    Mechanical Remediation Method GuidanceRevised June 2025Describes the conditions when we will allow the application of a mechanical remediation method.
    Non-Concrete Tank RequirementsEffective January 2024Outlines requirements and procedures for non-concrete tanks in areas with a high-water table.
    One Compartment Septic TankRevised December 2024Updated to clarify situations where policy applies.
    Operation and Maintenance (O&M) Firm Technician-Only GuidanceEffective November 2024Outlines roles and responsibilities of certified O&M technicians.
    Record Drawing GuidanceRevised August 2024Updated to clarify requirements for subsurface drip record drawings.
    Record of Existing Septic System LocateEffective March 2025Septic system locate site plan for existing systems without records.
    Remediation ProcedureEffective July 2026Use this guidance document to assist you when you perform a remediation.
    RSS Deficiencies with ResolutionsRevised April 2023Updated to meet remodel guidance. 
    Substandard Agreement ProcedureEffective June 2026Use these instructions to complete and submit a recorded agreement.
    Tank Repair or Replacement RequirementsRevised October 2025Updated to meet Washington Administrative Code (WAC) requirements.

    Individual Well Procedures

    Waivers

    Resources

    Questions?

    You can email us or call (253) 649-1925.