On-site Sewage
Asotin County On-site Sewage System Code
Promote and protect the public health, safety and general welfare; achieve effective long term sewage treatment and effluent dispersal; and to ensure that on-site sewage systems adequately support complete build out of subdivision lots, safeguard aquatic habitat, and protect waters of the state.
Signs of Septic System Failure
A failed or malfunctioning septic system is a risk to human and animal health and can pollute the environment.
Why Maintain Your Septic System
Like most components of your home, septic systems require routine maintenance.
EPA Homeowner Septic Smart Guide
A Homeowners’ Guide to Septic Systems.
Washington State Approved OSS Tanks
List of Registered Sewage Tanks
OSS Lid Safety
Prevent a Tragedy
Office of Wastewater Management Information
OWM supports the Clean Water Act by promoting effective and responsible water use, wastewater treatment, disposal and management and by encouraging the protection and restoration of watersheds.
Washington State Standards and Guidance
Wastewater Forms and Publications
EPA Onsite Wastewater Treatment Systems Manual
Regulatory standards, voluntary management approaches, and financial and technical assistance to states, Tribes, communities, and regulated entities to protect human health and aquatic ecosystems, reduce flooding, and protect the nation’s infrastructure investment.
Hiring An OSS Professional
There are several types of septic system professionals which provide different services at different stages of a septic system's lifetime.
Quick Tips & Videos
Septic System Basics Video
The basics of how on-site sewage systems function and the steps you should take to keep your system working well.
An on-site sewage system (OSS) is commonly referred to as a septic system or septic tank. OSS is used when a house is not connected to the city sewer system. Many houses in Asotin County use OSS. The major benefit of OSS is that you are able to comfortably live where the city sewer system does not go.
The homeowner is responsible for the installation, maintenance and repairs of their system. Failed systems can result in sewage reentering the home or leaking into the environment. Local and state code provides guidance to ensure a safe, effective and long lasting system. You can read more about the Washington Administrative Code (WAC) that relate to OSS to learn about the responsibilities of the homeowner.
Asotin County OSS code can be found below. This code provides information that specifically addresses the unique needs of Asotin County.
OSS System Application
The OSS Installer Test must be completed and submitted to ACHD prior to any OSS installation. OSS installations that require a permit include New Residential OSS Installation, Tank Replacements, Modifications to an OSS, Minor Repairs of an OSS, or Installation of a commercial OSS. A permit is not required for replacement, addition, or modification of broken or malfunctioning building sewers, risers and lids, sewage tank lids, sewage tank baffles, sewage tank pumps, pump control floats, pipes connecting multiple sewage tanks, and OSS inspection boxes and ports where a sewage tank, treatment component, or soil dispersal component does not need to be replaced.
Homeowner OSS System Installer Test
In Asotin County, the only persons allowed to install an On-Site Sewage System are licensed OSS Installers or Homeowners. Homeowners, or their immediate family members, may install an OSS every two years for a home that they inhabit and/or intend to inhabit for at least two years after construction if they meet the following requirements:
- Homeowners must successfully complete a test for competency administered by the District.
- Homeowners must follow the approved design.
- Homeowners who utilize the help of any individual, who is not a licensed installer under Asotin County Health District, bear the responsibility to ensure the OSS is correctly installed.
ACHD must give express permission for a Homeowner to install an OSS.
OSS System Record Drawing
After final inspection of the OSS is completed by ACHD, the installer must complete and submit this form before an “Operational” Permit is issued.
Caring for Your OSS System
Routine maintenance and minor repairs are necessary to ensure the system will last a long time. OSS systems that are properly built and maintained can last for decades. System failures are more likely to happen in tanks that were poorly designed or lack regular maintenance. Systems also do eventually need to be replaced as they do not last forever.
OSS tanks should be pumped every 3-5 years. You may need to have your tank pumped more often if your tank is undersized for the usage or if your tank is older.
System owners may not be aware that their tank is starting to fail. Regular pumping of the tank helps ensure the system is still functioning as it should. System failures can pose a risk to the environment and health.