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The Public Health On-site Sewage System (OSS) Program helps to ensure that over 85,000 septic systems including 192 septic systems in Seattle are safe. Septic systems treat wastewater when homes and buildings are not connected to public sewer systems. The OSS Program provides educational, advisory and permitting services for owners of septic systems and certifications for several septic professionals.

Special services and projects

Healthy Beach Project

Public Health continues to work with Vashon-Maury Island residents to document improvements to water quality, find sources of excessive bacteria, and, where possible, eliminate these sources.
Learn more: www.kingcounty.gov/oss/pic


Contact us

Environmental Health Services
14350 SE Eastgate Way
Bellevue, WA 98007

Phone: 206-477-8050 (answered until 4:00 pm)

Fax: 206-296-9792

Office hours:

  • Monday, Tuesday, Wednesday & Friday:
    8:00 am – 4:00 pm

  • Thursday:
    9:00 am – 4:00 pm

Call our "Sanitarian of the Day" (SOD) for technical and general questions at 206-477-8177
The SOD is available Monday, Wednesday and Friday 8:00 am - 10:00 am only. If the sanitarian does not answer, he or she may be helping someone at the counter. Please leave a voice message and we will return your call as soon as possible.

Link/share our site at www.kingcounty.gov/oss