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Maintaining Your Septic System

Over 50% of the residents in Clallam County live in homes that are not served by public sewers, but by a septic tank and drainfield system.  Maintenance of these systems is important if they are to continue to work properly over a long period of time, and in order to protect our health and environment.

Also, the 2005 onsite septic system regulations (WAC 246-272A) state that septic system owners shall “assure a complete evaluation of the system components to determine functionality, maintenance needs, and compliance with regulations and any permits.”  The new State regulations require that homeowners inspect and maintain their septic system to ensure it is functioning properly.  Visit the septic system Operation and Maintenance (O&M) page for more information.

Take Care of Your Septic

The Environmental Health Services (EH) has published an artistic and informative handout titled `Take Care of your Septic´(2.1MB PDF) available online.  This handout is full of information about how systems work, the do's and don'ts of septic system use, and tips to follow to help your system last as long as possible.  The handout is also available in hardcopy from the Environmental Health office; please contact us to request a copy.

How a Septic System Works

The typical septic system consists of a septic tank and some type of a disposal field.  The septic tank collects the waste water from the kitchen, bathroom and laundry and separates the solids from the liquids.  The septic tank is divided into two chambers.  In the first chamber, heavy solids settle to the bottom to form a sludge layer; greases and soaps float to the top to form the scum layer.  Bacteria begin to work on the solids and partially digest them.  The liquid portion called effluent flows into the second chamber where additional settling and digestion occur.  From there, the effluent flows into a drainfield, which typically consists of a series of perforated pipes in trenches.  Bacteria and viruses are removed as the effluent moves through the soil and dries out.


Why is Maintenance Necessary?

Septic systems need proper care and maintenance. We have all heard stories about septic systems that have worked well for many years without any maintenance or care. These are exceptions to the norm.

Eventually, the bacteria in the septic tank become unable to digest all of the solids in the tank. The scum and sludge layers begin to build up. This may cause the solids to block the sewer line from the house or pass out into the drainfield and clog the pipes. Clogged drainfields may result in surfacing sewage, offensive odors, plumbing backups, or contamination of surface or ground water.

Repairs to a system can also be costly. It costs less to maintain a system than to replace it.

Maintaining a Septic System

The septic tank should be inspected at least every three years for conventional gravity septic systems, and pumped when necessary.  A system with a pump should be inspected annually. To inspect the tank, uncover both the inlet and outlet access covers. Use a stick to measure the thickness of the scum and sludge layers. It is time to pump the tank if the sludge is more than 12 inches thick, or if the scum is more than 6 inches deep or within 3 inches of the bottom or top of the outlet baffle. Inspect the inlet and outlet baffles and replace them if they are broken or missing. The baffles help keep the liquids from being stirred up. They also keep scum and sludge from leaving the tank and clogging the drain lines. Clallam County Environmental Health has developed a Homeowner Do-It-Yourself Septic System Inspection certification program (Septics 201) that details how to inspect your septic system.

The drainfield often requires little maintenance by a homeowner. It should be checked from time to time to make sure there is no surfacing sewage. Vegetation should be kept to a minimum. Roof drains should be directed away from the drainfield. A thick growth of grass or spongy ground may indicate a potential failure.

Do not park or drive heavy vehicles over your drainfield.  Pipes can get broken and compacted soil compacted may no longer be able to absorb the liquid wastewater or effluent.

Environmental Health Services has printed literature available with more information to help you inspect your septic tank and drainfield.  See also our Septics 201: DIY Septic System Inspection Program to become certified to inspection your septic system and submit online inspection reports directly to us. We also have brochures at our office about maintaining specific types of septic systems.  Some additional information is also available online from the Washington State Department of Health:

Washington State University Extension Office also offers information about septic systems.  On their Publications and Educational Materials page, use the Search tool to find “septic systems”.

In addition, our newsletter focuses on septic system operation and maintenance.

Drainfield Landscaping

Carefully choosing the plants you have growing over your drainfield is an important part of taking care of your septic system.  Avoid trees, shrubs, and water-loving plants with deep roots.  These can clog or damage the pipes in your system.  Grasses, mixed wildflowers, and ground covers with shallow roots are good alternatives.  For more information please visit our landscaping your drainfield page.


A septic tank additive is a product that is sold with the claim that using it will improve the performance or aesthetics of your septic system. To our knowledge, there is no additive on the market which will improve the operation of a normal septic tank.  They may actually do more damage than good to your septic system.  You’re better off to bank the money for a future pumping. 

The Washington State Department of Health reviews and approves septic tank additives, and provides consumer protection.

Return to the On-site Septic Systems main page.

Clallam County Health & Human Services
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