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Most of the on-site sewage system (OSS) record drawings, also known as as-builts, dating from 1998 are available online. The record drawings include both new construction and repairs to failing systems. Many older records are available but may not be as accurate, legible, or detailed as recent record drawings, as regulations have become more prescriptive.

Here are the most 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. The scanning process is done by a third party once we have an adequate quantity. 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. Also, some parcels have been re-platted since the original documents were submitted. In these cases it is helpful to provide the original house address.

If a record drawing is not found during your search, please send an email to with the parcel number and street address and we will search our files for the drawings (please allow up to five days for a response). If you need additional assistance, please call 206-477-8050.

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

Enter the parcel number in the "Value" 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 that parcel.

If you are having trouble finding records for your property and you don’t know the parcel number, try searching by just the house number and picking your property from the resulting list.