Approved / Registered On-site Products
Additive Review Application for Approval (Word) – NOTE: Approval by DOH only means that DOH has determined that the additive is not harmful or toxic; it does not mean that DOH endorses the use of any additive product for sewage systems.
Annual Renewal Form, Proprietary Products (PDF) – An electronic form used to request renewal for a registered proprietary product for use in Washington State. This form includes the required Verification Affidavit.
Application for Sewage Tank Registration (Word) – An electronic form used to apply to register sewage tanks for use in Washington State. For renewals complete Renewal Application and Verification Affidavit for Sewage Tank Registration (Word).
Application for Registration Proprietary Distribution Product (PDF)
Application for Registration Proprietary Treatment Product (PDF)
List of Approved On-site Sewage System Additives (PDF) – NOTE: Approval by DOH only means that DOH has determined that the additive is not harmful or toxic; it does not mean that DOH endorses the use of any additive product for sewage systems.
List of Registered On-site Treatment and Distribution Products (PDF)
List of Registered Sewage Tanks (PDF)
Renewal Application and Verification Affidavit for Sewage Tank Registration (Word). This form must be completed when renewing sewage tank registration.
Home Owner / Property Manager Publications
OSS Homeowner Education – Learn about your on-site sewage system.
Tier One Greywater System Checklist and Irrigation Area Estimation Tool (PDF)
Tier Two and Three Greywater Subsurface Irrigation Systems - Guidance (PDF)
Understanding and Caring for Your Mound System (PDF)
Understanding and Caring for Your Pressure Distribution System (PDF)
Understanding and Caring for Your Sand Filter System (PDF)
Understanding and Caring for Your Septic System (PDF)
Recommended Standards and Guidance (RS&G) Documents
Dosing Gravity Drainfield Systems (PDF)
Glossary of Terms for RS&Gs (PDF)
Gravelless Distribution Products (PDF)
Holding Tank Sewage System (PDF)
Intermittent Sand Filter Systems (PDF)
Pressure Distribution Systems (PDF)
Proprietary On-site Wastewater Treatment Products (PDF)
Recirculating Gravel Filter Systems (PDF)
Remediation Technologies and Processes (INTERIM) (PDF)
Sand Lined Trench Systems (PDF)
Stratified Sand Filter Treatment Systems (PDF)
Water Conserving On-site Wastewater Treatment Systems (PDF)
Sewage Tanks Information
Application for Sewage Tank Registration (Word) – An electronic form used to apply to register sewage tanks for use in Washington state.
List of Registered Sewage Tanks (PDF)
Renewal Application and Verification Affidavit for Sewage Tank Registration (Word) – This form must be completed when renewing sewage tank registration.
Technical Information and References
Basic Principles of Onsite Sewage (PDF) – This document was prepared prior to the adoption of the 1995 on-site sewage rules. For items specific to Washington State rules see Chapter 246-272A WAC
Design Guideline for Gravity Systems in Soil Type 1 (PDF)
EPA Onsite Wastewater Treatment Systems Manual, 2002 (PDF) – Referenced in Chapter 246-272A WAC, which governs on-site wastewater treatment systems.
Evaluation of the Effectiveness of Chapter 246-272A WAC, reporting year 2017, as required by Chapter 246-272A-0425:
Granting Waivers from State On-Site Sewage System Regulations, An Application Guide for (PDF)
Guidelines for Test Pit Construction for On-site Sewage Systems (PDF)
Nitrogen Reducing Technologies for Onsite Wastewater Treatment Systems Report (PDF)
On-Site Management Plan Guidance for Local Health (PDF)
On-Site Wastewater Advisory Committee Summary Report (PDF)
Pipeline Separation Design and Installation Reference Guide Version 9 (PDF) – Co-authored with Washington State Department of Ecology
Puget Sound Local On-site Sewage Management Plans - A Report to the Legislature (PDF) – The 2008 Progress Report Fulfilling 3SHB 1458 Requirements - Section 11
Puget Sound Septic System Management Programs - Best Management Practices Reference Manual (PDF) – Technical manual providing background and describing the many issues, elements, and activities of the on-site sewage management programs carried out around Puget Sound.
Tier One Greywater System Checklist and Irrigation Area Estimation Tool (PDF)
Tier Two and Three Greywater Subsurface Irrigation Systems - Guidance (PDF)
Vertical Separation (PDF) – A review of available scientific literature and a listing from fifteen other states.
On-Site Sewage System Ultraviolet Disinfection Study
Technical Issue Reports
The following Technical Issue (DRAFT) Reports summarize the available literature about on-site wastewater topics of special interest during the rule development process of the current on-site sewage system rules and regulations (WAC 246-272A). Please note that these reports are drafts and may undergo modification from time to time.
Application of Treatment Standards 1 and 2 (PDF)
Disposal Component Reductions - Special Features and Applications of Drainfield Products (PDF)
Disposal Treatment Options - Highly Pretreated Effluent (PDF)
Sand and Media Specifications (PDF)
Septic Tank Effluent Values (PDF)
Wastewater Quality / Strength / and Content (PDF)