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Update (4/4/17)

You may have received or have seen a septic system maintenance flyer that incorrectly describes King County inspection requirements. Your maintenance schedule depends on what kind of system you have and other factors related to your property. When hiring a King County certified On-site System Maintainer, know the type of septic system you have, and follow the maintenance schedule designed to help keep your septic system working for many years.

How an inspection will benefit you

Routine maintenance may lengthen the life of your septic system.

  • Saves money - an operation and maintenance inspection is a bargain compared to the cost of repairing or replacing a failing system, which can be very expensive.
  • Reduces the risk of failure - a failing septic system may result in a sewage back-up inside your home causing costly repairs or sewage may surface in your outside yard where your family and pets may be exposed.
  • Rather than regularly scheduled septic tank pumping, have your tank inspected and only pumped when needed. Different size septic tanks, the use of a garbage disposal, and other factors may increase or decrease how often your tank needs pumping. If the septic tank is not pumped when needed, it may cause solids in the tank to flow into the drainfield and clog the system.

The septic system owner is responsible for operating, monitoring, and maintaining their septic system. Protect your family’s investment by managing your operation and maintenance inspection and pumping schedules.

Contact a certified On-site System Maintainer to inspect and monitor your system. Become familiar with your system type and how your family needs e.g. garbage disposal, so that you understand how often it should be inspected.

To learn more about septic system inspections, please visit the following web sites from the Washington State Department of Health:

When should you hire an On-site System Maintainer?

The frequency of inspections depends on the type of your septic system.

Gravity systems:      

It is the owner's responsibility to inspect their systems either themselves or by a certified Pumper or On-site System Maintainer

  • Every three years

Pressure Distribution systems:

  • Annually

Proprietary system such as an ATU, Orenco, drip irrigation, and others products:

  • Annually or more often if required by the manufacturer

Mound, Sand Filter, or Sand Filter to Mound systems:

  • Annually

What happens during an inspection?

The On-site System Maintainer (OSM) will inspect your system components:

  1. Septic and pump tanks
  2. Treatment component (if applicable)
  3. Distribution system
  4. Drainfield and the reserve areas

To learn about options available for financial help with septic system repairs read On-site sewage system loans or grants