OSS Failure Rates Inflated

The following is a report that is used to substantiate the high failure rate and public health risk caused by Onsite Sewage Systems (OSS).   However, the survey covers several years and the number of years vary.   Allowing for ANNUAL  “Failure” rates, the reality is between 2.3 and 8.9%.   This data is used to establish State Rules regarding residential OSS …. and yet it is very, very wrong!           Read on:



What are Septic System Failure Rates, and how are They Used in Thurston County?
Some community members have expressed concerns about how county staff and the Thurston County On-site Sewage System Management Plan Update describe and discuss septic system failures and failure rates. Thurston County wants to be responsive to our community’s concerns,
and drafted this document to help address this issue.

Table 1: Failure Rates Found During Sanitary Surveys in Thurston County

Survey Area and (year) Number of Systems Evaluated Number of Failing Systems Failure Rate
Eld Inlet (1990-96) 564 93 16%
Eld Inlet (2012-14) 102 17 17
Henderson Inlet (1996-99) 58 8 14
Nisqually Reach (1994-96) 123 32 26
Nisqually Reach (1996-99) 42 12 29
Summit Lake (1992-97) 330 57 17

Prepared by Thurston County Public Health and Social Services
Point of Contact: Art Starry, Environmental Health Division Director
Email: starrya@co.thurston.wa.us
Phone: (360) 867-2587
April 11, 2017

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