Septic System Maintenance & Evaluation

Septic systems, also known as on-site sewage systems (OSS), treat sewage so it doesn’t contaminate local rivers, lakes, and groundwater. Just like your home or car, your septic system needs to be monitored and maintained regularly. This can reduce the chance that you’ll need to do major, costly repairs to your system because you’ll catch small problems before they become big ones.

What is a septic system evaluation?

A septic evaluation is an inspection of all the components of your septic system: septic tank, pump tank (if you have one) and drainfield.

Some of the things checked during an evaluation are:

  • The tanks are checked to make sure they are not leaking.
  • The sludge and scum levels are measured in the tank to determine if the tanks should be pumped.
  • The drainfield is checked with a flow test to see if it is performing properly and inspected to see if any sewage is pooling.
Septic system maintenance infographic
Click on the image to view a larger version.

You can hire a professional to perform a septic evaluation. Depending on the type of system you have and the purpose of the evaluation, you can also do it yourself. To learn if and how you can complete your own evaluation, see “Who can perform a septic evaluation?”.

When do you need a septic evaluation?

Some types of septic systems need to be checked more often than others.

  • Conventional gravity systems need to be evaluated every 3 years
  • All other types of septic systems need to be evaluated once a year (unless the manufacturer specifies they should be inspected more frequently)
  • All septic systems that serve a food service establishment must be inspected once every year.

When a property is offered for sale, a current inspection report, called a “Report of System Status” (ROSS), must be on file with the health department.

For information about your septic system's records, contact us at (360)778-6000. You can also look up information about your permit here.


Licensed Septic Professionals in Whatcom County:

Who can perform a septic evaluation?

A septic evaluation can be done by a licensed professional, also called an O&M Specialist. These professionals work for private businesses and have been licensed by the health department.

Homeowners can also become certified to complete their own septic evaluation by taking a free training offered by the health department.

Homeowners CANNOT complete their own evaluations if any of the following apply:

  • The septic system is connected to a community drainfield
  • The system serves a restaurant or other food service establishment
  • The system is being evaluated for a sale or property transfer
  • The septic system uses a proprietary technology (Some examples are Glendon Biofilter, OSCAR, and ATU)
  • The system was considered “non-conforming” when it was replaced

Please contact us at (360)778-6000 if you are unsure your septic system uses proprietary technology or was “non-conforming”.


How much does a septic evaluation cost?

Septic evaluation costs vary depending on your specific system. For more information on costs, you may contact any of the licensed professionals on this list to get a quote.

 Financial help is available for failing septic systems or repairs in some cases.

  • Whatcom County Septic Maintenance Rebate Program – helps cover the costs of septic evaluations, pumping, and equipment installation. Learn more here
  • Craft3 - a local nonprofit financial institution that provides loans for septic repairs and replacements in Whatcom County. To learn more or apply, contact Craft3 at 1-888-231-2170 ext. 125 or www.craft3.org/CleanWater.