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Most of the on-site sewage system (OSS) records including site designs, historic inspection reports, record drawings (also known as as-builts) in King County records are available online. They include both new construction and repairs to failing systems. Approved OSS site design applications submitted online since May 2019 are also available.

Record search tool

Search for your record drawing using the following steps:

  1. Enter the parcel number (use only numbers – 2925001011 not 292500-1011) in the "Parcel Number/APN" box below and click on the Search button. A list of available records will be displayed. A search resulting in "0 rows" means no electronic septic system records were found for this parcel number.

    If you don't know your parcel number, use King County's ParcelViewer to find it. Enter your address in the search bar, click on the Search button, and your parcel number will be shown to the left of the map.

  2. If no results are displayed, ERASE the parcel number.

  3. Enter ONLY the house number in the “House Number” box below. Then click on the Search button. A list of available records with that house number will be displayed.


As-built drawing search tool (may take several seconds to load on your screen)

Some common reasons that record drawings are not available online:

  • The house was built prior to the early 1970s.
  • The OSS was installed without a permit.
  • The OSS designer never submitted the final construction documents to this department.
  • The record drawing may be in our microfiche files, but has not yet been scanned into the electronic database. You may wish to contact the septic system designer or engineer for a copy.
  • The property address or parcel number has changed. Some addresses have changed over the years, especially within areas newly incorporated into cities. Some parcels have been re-platted since the original documents were submitted. In these cases, it is helpful to search with the original house address.
  • Many pre-1998 records are available, but may not be as accurate, legible, or detailed as recent record drawings.

If you do not find a record drawing, please send an email to Include the parcel number and street address and we will search our files for the drawings.

Please allow up to five business days for a response. Our reply (from PAEGAT25) may go to your email's Spam folder.

If you need additional assistance, please call 206-477-8050.

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