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Septic System Education

Program Contact: Kendall Carman Master Gardener/Small Farms Coordinator
(360) 427-9670 Ext. 682 •

Online Resources

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Mason County Public Health – Onsite Sewage System Program

On-site Sewage System Educational Information

Regulations for On-Site Sewage

User’s Manual – Care and Feeding of Your Onsite Septic System



How to find your as-built and maintenance records

Maintenance records:

Diagram of your system:

Washington Department of Health Videos


DIY Septic Inspection

Septic Systems 101

How do Septic Systems Work?


A properly functioning septic system works like a miniature wastewater treatment plant:  bacteria, which need food (your waste) and air, do most of the work.

    1. Waste leaves the home, flowing into the septic tank, where solids settle out to the bottom and a scum of oils etc. forms on the surface.
    2. The liquid that remains flows out of the tank and into the drain field where it enters the soil through a series of perforated pipes.
    3. Helpful bacteria living in the soil and remove organic matter and potentially dangerous pathogens from the water before it percolates down into the water table.

How Do I Know If My Tank Needs To Be Pumped?


Solids build up at the bottom of your tank – over the course of 2-5 years – until they overflow. This can clog the pipes in your drain-field and cause major problems. Inspect your scum and sludge layers every year so you’re not caught by surprise.

Factors that impact sludge and scum buildup:

  1. Avoid using garbage disposals if you’ve got a septic system, they can speed up the accumulation of sludge.
  2. Throw away oils and greases, they will contribute to the scum layer.
  3. The number of people in the house. Growing family? you’ll need to pump your tank more often.
  4. The size of the tank. Tanks are typically 1000 gallons, but larger tanks can accommodate more waste.

Certified septic pumpers in Mason County

Certified Septic Operations and Maintenance Specialists

Image courtesy of the Mason County Health Department