All About Septic

Source: https://snohomishcountywa.gov/ and https://www.epa.gov/septic

How does a septic system work?

1. All water runs out of your house from one main drainage pipe into a septic tank.

2. The septic tank is a buried, water-tight container usually made of concrete, fiberglass, or polyethylene. Its job is to hold the wastewater long enough to allow solids to settle down to the bottom forming sludge, while the oil and grease floats to the top as scum. Compartments and a T-shaped outlet prevent the sludge and scum from leaving the tank and traveling into the drainfield area.

3. The liquid wastewater (effluent) then exits the tank into the drainfield.

4. The drainfield is a shallow, covered, excavation made in unsaturated soil. Pretreated wastewater is discharged through piping onto porous surfaces that allow wastewater to filter through the soil. The soil accepts, treats, and disperses wastewater as it percolates through the soil, ultimately discharging to groundwater. If the drainfield is overloaded with too much liquid, it can flood, causing sewage to flow to the ground surface or create backups in toilets and sinks.

5. Finally, the wastewater percolates into the soil, naturally removing harmful coliform bacteria, viruses and nutrients. Coliform bacteria predominantly inhabits the intestines of humans or other warm-blooded animals. It is an indicator of human fecal contamination.

Source: https://www.epa.gov/septic/how-septic-systems-work

What kind of system do you have?

You can find the type of your septic system and its location by finding your system's "As-Built Drawing" on the Snohomish County Health Department website in their Online RME database.

Learn how to look up your septic system As-Built by watching this video or viewing this instruction sheet.

How do I take care of it?

Visit the Snohomish Health Department's Savvy Septic Program to view upcoming workshop dates, register for workshops or sign up to receive notice of upcoming workshops in their quarterly newsletter for septic system homeowners. 

Each type of system is required different care. See the guides on the Snohomish County’s website here.

Do not plant anything overtop your septic system or reserve area that isn’t on the approved list. Don’t park your car, drive over, or build on top of your system.

What not to put down your drain on septic

Keep these out of the drain and toilet:

• kitchen scraps, fats, oils, grease

• baby wipes, tissue, paper towels, or extra plush toilet paper

• floss, hair, feminine products, condoms

• kitty litter

• septic system additives

• old medicine

• harsh chemicals, cleaners and paints

What kind of maintenance does it require?

• Routine inspections every 3 years

• Pumped at a frequency recommended by the inspector

• Clean the tank outlet screen yearly (if you have one)

What do I need to know about septic systems and real estate?

When you own a home with a septic system, you will need to provide all your records associated with your system (reports, as-built, permits, etc). The buyer will ask for you to have your system inspected. Depending on the county your home is in, you will be required to provide the system without any deficiencies.