Septic Tank System Services offered in King County, WA

Areas We Serve


  • Auburn
  • Buckley
  • Carnation
  • Clyde Hill
  • Renton
  • Seattle
  • Snoqualmie
  • Tacoma

Every property that is serviced by an onsite septic system or OSS in King County or Pierce County must be pumped and inspected when the property is transferred. Lilly’s Septic Inspection Services, your choice for septic system repairs in King County, can provide pumping & inspection in one convenient appointment.  Not all local septic companies do King County home sale inspections so make sure you hire an experienced company with the proper certifications and training for your inspection. With Lilly’s Septic Tank Service we can do everything you need for your septic system so you don’t have to deal with multiple appointments or septic companies. We are certified O&M Professionals, Certified Pumping Professionals, and we hold the King County Master Installers license for repairs. The following information and links will help you prepare to sell a home in either King or Pierce County.

Septic System Requirements for the Sale or Transfer of Properties in King County

The Public Health departments in Seattle and King County require all sellers of properties with onsite sewage systems to have their on-site septic tank system inspected by a King County licensed On-site System Maintainer (OSM). The inspection must be completed, and a copy of the report must be given to both the buyer and the Public Health department before the transfer of title. The OSM must submit the property transfer report to King County environmental health through the online RME, King County’s reporting and public record system.

Fees and Services for King County

King County’s filing feel for OSS septic system inspections is $198.00. This fee will be included in your service invoice. The filing fee is collected by the O&M professional from the homeowner (or whoever is paying) and paid directly to King County. This is not a fee charged by Lilly’s Septic Tank Service, this is a King County fee, but we must have the funds prior to submitting the O&M sale inspection certification paperwork. Find out more about home sales and transfers in King County on the King County real estate sale inspection page.

OSSM Requirements

Before closing a home sale, the seller must record a notice of On-site Sewage System Operation and Maintenance Requirements (OSSM)* at the King County recorders’ office. This is a document that acknowledges the property is served by a septic system and describes the owner’s responsibilities for maintaining the system. The seller gives a copy of the recorded OSM to the buyer prior to closing. A declaration of receipt of the recorded OSM should be signed by the seller and buyer for their records (King County does not need a copy of this declaration of receipt).

*OSM – is also known as Form 22U by the Northwest Multiple Listing Service

As-Built Drawings with Lilly’s Septic Tank Service

AS-BUILT DRAWING – An As-Built drawing is a diagram of the septic system and shows where the septic tank, pump tank (if there is one), the d-box, and drainfield lines are located, as well as any other buildings such as sheds, garages, pools, etc. on the property. King County requires that an As-Built is submitted with the OSS Inspection paperwork – If KC does not have an as-built on file that can be submitted, then Lilly’s Master Installer/Professional OSM must draw a certified scale as-built drawing to be turned into KC with the paperwork. Fee applies and will be quoted (if necessary) at time of booking.

Contact Lilly’s Septic Tank Service with Questions

To check if there is an As-Built on file at the KC Health Dept, the As-Built lookup site can be found here: http://www.kingcounty.gov/healthservices/health/ehs/wastewater/owners/AsBuiltDrawings.aspx - If nothing is on file then request a copy of your as-built by calling the health department directly at 206-477-8050. Alternatively, Lilly’s septic (OSSM) Inspection Coordinator will obtain the As-Built via email from KC Health Dept for no charge after booking your inspection appointment. If there is no as-built available, the county will require us to draw a certified As-Built to submit the inspection paperwork. For more information on our offers and services in Maple Valley and throughout King County, give us a call today!

Lilly’s Septic Tank Service provides quality, environmentally-conscious, and expert Septic Tank Services to the King's County area of Washington.