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Wastewater Management

The Wastewater Management Program is responsible for the safe treatment and dispersion of domestic, non-industrial wastewater in areas of Washington not served by municipal sewage treatment works. 

Individual On-site Sewage System (OSS) (septic systems)

Individual and small (up to 3,500 gallons/day) on-site sewage systems are permitted and regulated by local health jurisdictions.  Department staff provide consultative and technical support to local health jurisdictions and develop/maintain guidance documents for various technologies.  Staff review proprietary wastewater system products to verify they meet testing protocol requirements and maintain a list of products meeting the requirements for use throughout the state.

Large On-Site Sewage System (LOSS)

Staff review and approve plans for on-site sewage systems designed to handle wastewater flows from 3,500 to 100,000 gallons per day and issue annual operating permits to all LOSS. Staff also review, approve, and maintain a registered list of septic tanks, pump chambers, and other tanks that are part of individual, small, and large on-site systems in Washington State.

Water Reclamation and Reuse

Staff working with Department of Ecology on public health aspects of permitted and proposed reclaimed water facilities. Staff work directly with those proposing minimum or zero discharge reuse and reclamation facilities and developments.

Forms and Publications

Find forms, recommended standards and guidance documents, and other publications here.

Greywater Reuse

Greywater is water used for washing from sinks, showers, clothes washers, and other sources that don't include human waste. New rules in Washington allow reusing some types of greywater for subsurface irrigation. Learn about the different characteristics of greywater, requirements on where and how it can be used, and much more.

Homeowner Education

Learn how you can care for your on-site sewage system (septic system), increase the life of your investment, keep people from getting sick and protect the environment.

On-site Sewage Systems (OSS)

Explains the importance of properly functioning OSS, how some areas are environmentally more sensitive to pollution from OSS, and the different roles state agencies, local health jurisdictions, and homeowners play in managing small on-site sewage systems.

Large On-site Sewage Systems

Program staff review and approve large on-site sewage systems (LOSS) project applications state-wide. 

Local Health Support

We provide technical assistance, guidance, and social marketing tools for local health jurisdictions to implement and build upon operation and management (O&M) programs for on-site sewage systems.

Training Opportunities

Links to classes and other learning opportunities are listed here.

Water Conservation

Water conservation guidance regarding wastewater and greywater recycling and links to the Water Use Efficiency Program (Office of Drinking Water) and the EPA's WaterSense Partnership Program

Related Links

This page provides links to other agencies and organizations that are involved with wastewater issues and regulation.

Contact Us

Phone numbers, office addresses, directions, and staff contacts are found here.  

Join our Wastewater Mailing Lists

Receive new information automatically by email.

You must join each list individually, and you can unsubscribe at any time.

  • Wastewater - Used to notify interested parties about general wastewater issues including updates to Recommended Standards & Guidance and proprietary product lists, announcing Technical Advisory Group meeting dates, wastewater newsletter publications, and other general state wastewater related topics.

  • Wastewater-LOSS - Used to update stakeholders and interested parties on Large On-site Sewage System Program activities.

For questions, please contact the Wastewater Management Section at, or call 360-236-3330.