Environmental Health Programs - On-site Sewage


Environmental Health Specialist


An environmental health specialist permits all county septic systems and licenses septic system installers and septic tank pumpers. On Site Sewage is responsible for the safe treatment and dispersion of domestic, non-industrial wastewater in areas of Kittitas County to ensure the safety and sanitary disposal of waste.

Step by step process to installing an on-site sewage system

  1. Site Evaluation
    To obtain an OSS installation permit you will first need to have a site evaluation on the proposed project parcel. The site evaluation is performed by an Environmental Health Specialist from the Kittitas County Public Health Department. This evaluation of soil and site characteristics will determine the suitability for an OSS on the parcel. During the evaluation, the type of OSS (gravity, pressure distribution, or alternative system), along with the soil loading rate, and other landscape and environmental factors will be determined. To obtain a site evaluation, submit the site evaluation application (link to application is below) and fee to the Kittitas County Public Health Department. Once the application has been submitted two holes six feet in depth and three feet in width with a step side access will need to be placed in the proposed drain field and reserve drain field locations on the parcel.
  2. OSS Design
    After the site evaluation is complete, the next step will be to have an OSS design prepared by a licensed on-site designer. Homeowners wanting to prepare their own OSS system design are allowed to do so, but only for gravity flow systems. If you wish to prepare your own gravity flow system design, you are required to schedule a pre-design meeting with an Environmental Health Specialist and pay an additional fee. All other types of OSS systems must be designed by a licensed on-site designer.
  3. Installation
    Once the OSS design has been reviewed and approved, an OSS installation permit will be issued (fees for permit vary.) This installation permit is valid for one year from the date of issuance. A one-year renewal permit may be issued if the application is submitted before the expiration date of the original installation permit. Homeowners are allowed to install their own OSS system. A Kittitas County OSS Installers license is required for all septic system installers and septic tank pumpers contracting work in Kittitas County. These licenses are available through the Kittitas County Public Health Department.
  4. Inspection
    All OSS systems installed must be inspected by an Environmental Health Specialist prior to back fill. The installer or designer may schedule these inspections directly with the Kittitas County Public Health Department. For all septic systems a final approval cannot be issued on the inspection until an As-Built is submitted. It is also important to note that for all pressurized septic systems in addition will need to be electrically hardwired and properly set before a final approval can be issued.


Licensed designer and installers may request an inspection online. You will receive a confirmation email once the requested inspection has been scheduled.


Unified Site Plan
Sewage system installation permit renewal
Sewage system installation permit application
Privy permit application with covenant
Application for Site Evaluation

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