Septic systems

A large number of permitted septic systems (or on-site sewage systems (OSS)) are located in the Lake Whatcom watershed. Proper care and maintenance of your septic system is critical for the protection of our water quality. Learn more about septic system maintenance at the Whatcom County Department of Health website.


A failing septic system can impact more than just your wallet, it can:

  • Allow potentially harmful bacteria and other disease-causing microorganisms to enter our drinking water
  • Result in greater algae and plant growth in the lake as a result of added nutrients
  • Result in decreased dissolved oxygen in the lake
  • Result in people coming into direct contact with raw sewage

Care and Maintenance

Avoid septic system failure through regular care and maintenance.

  • Septic evaluations are required every 1 or 3 years, depending on the type of system you have. Not sure what type of system you have? Check with the Whatcom County Health Department.
  • Have your system pumped by a licensed septic professional when the solids in the tank reach 1/3 of the total tank volume. The solids in the tank are measured during an evaluation.
  • Avoid overloading your septic system:
    • Check your sinks, toilets, and showers regularly for leaks
    • Run your dishwasher, washing machine, and showers at different times
    • Have a break in between running loads of washing
    • Redirect surface water runoff away from the drain field
  • Be aware of what is going down the drain and entering your system:
    • Avoid using your garbage disposal as it may mean your system needs to be pumped more regularly
    • Avoid flushing products designed to kill bacteria down your drain/toilet as these may also kill the essential bacteria needed to make your septic system work properly (antibiotics, products containing bleach, polishes, caustic drain openers)
    • Use cleaning products that are safe for septic systems (OSS)
  • Keep grease and oils out of your drains.
  • Avoid using any products containing phosphates or nitrates as these may enter the water supply.
  • Flush only human waste and toilet paper down the toilet.
  • Septic Maintenance can be an unexpected expense. Whatcom County has a rebate program for qualified homeowners. Learn more here.

Septic System Failure

If you are having a problem with your septic system, like sewage surfacing in your yard, contact Whatcom County Health Department at (360) 778-6000 immediately.

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