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Founded in 1990, the Washington On-Site Sewage Association is a non-profit trade association serving the on-site wastewater industry. Today the organization has grown to encompass all disciplines of the industry, has continued to expand its impact, and supports improvement in all of the industry's professions. These professional areas include regulators, designers, installers, operations and maintenance support, and manufacturers/suppliers operating in the state of Washington. WOSSA has since been a leading onsite professional membership association for the onsite septic industry with key consideration to the Consumer, Public Health and the Environment.

Mission Statement

“WOSSA exists to represent our diverse industry through education, certification, legislative involvement, ethical standards and technical advancement to elevate the professionalism within all segments of our Onsite Waste Water Community.”

With more than 300 industry professional members and member companies in the state of Washington, WOSSA serves as the voice of the on-site industry and the resource for our members in service to our communities.

We carry out our mission through education, advocacy, information, and our community. Each year WOSSA;

  • Serves as an advocate of the onsite profession in our communities through involvement in our state legislation and local governments
  • Sponsors numerous continuing education experiences to help onsite professionals maintain or achieve their mandatory licensure / certification
  • Provides Web-based resources for continuing education and emerging industry professionals
  • Hosts the annual WOSSA Conference
  • Helps support and give back to our on-site community through the annual WOSSA Scholarship Program
  • Champions the onsite industry’s future by enhancing public belief in the value of long term decentralized wastewater strategies

Organizational Structure

The Washington On-Site Sewage Association is governed by a Board of Directors, a statewide elected governing body that provides long-range strategic leadership. The Board is composed of elected WOSSA officers, including the president, vice president, past president, secretary, and treasurer; elected representatives from each of WOSSA’s 4 regions; a supplier’s and manufacturer’s representative; an operations and maintenance representative; a pumper’s representative; a designer’s representative; an installer’s representative; and a public regulator’s representative from one of the local health jurisdictions.

Board Of Directors

Visit the Board of Directors Directory for Leadership information and member profiles. If you’re a WOSSA member, request approved minutes from past board meetings.

WOSSA Board Directory

Decentralized Wastewater Technology

“Decentralized system” has become a commonly-used term to describe a wastewater treatment system that treats and disperses wastewater from individual homes or a cluster of homes at or near the source of the wastewater discharge.  Decentralized systems include onsite and cluster treatment systems.  Systems may serve a cluster of homes, a subdivision or small community as well as commercial and industrial complexes.  If multiple sources are served by a cluster system, a collection system may be included to receive and convey the wastewater to a combined treatment and dispersal component.  These systems take advantage of the vast capacity of soil to remove or transform pollutants that are in the effluent as it percolates through the soil thereby avoiding point discharges to surface waters and maintaining the quality and quantity of our groundwater.
By definition, onsite wastewater management systems are a ‘green technology’ because treated effluent recharges local aquifers.  A new innovation in decentralized wastewater management is the reuse or recycling of treated effluent.  With appropriate safeguards, local regulations or bylaws may allow the treated water to be used for irrigation, toilet and urinal flushing or make-up water for commercial boilers.  These applications reduce the demand for potable water and aid in the protection and preservation of the available water sources.

As society demands more efficient use of financial resources and sustainable environmental wastewater management, the use of managed decentralized wastewater treatment systems is a key support structure for wastewater reuse.  This requires a distributed management system supported by trained professional service and maintenance providers.