Skip to main content

How Does a Septic System Work?

Your household sends into your septic system not only human waste, but also all other liquid wastes—bath water, kitchen and bathroom sink water, laundry water, and water softener backwash. So here’s what happens underground when you flush, do laundry, or use the sink or tub:

The heavier solid matter settles to the bottom of the septic tank, where microorganisms feed on the waste and break it down. Lighter fats, oils, and greases float to the top of the tank, forming a scum that may eventually break down or be skimmed during system maintenance.

The liquid that remains is still sewage. As it exits the tank, it contains disease-causing bacteria and viruses, as well as other contaminants. Another treatment step is needed before the sewage reaches the groundwater or surface water.

Think at the sink, and don’t overload the commode. 

Consider what you put down your sink and toilet. Limit the use of your garbage disposal. Avoid using common household items that can clog your system or kill the microbes underground that you need to treat the wastewater.

  • “System Cloggers” -- diapers, baby wipes (even ones marketed as “flushable”), cat litter, cigarettes, coffee grounds, fats, grease, solids, feminine hygiene products and prophylactic devices.
  • “Treatment  Killers” -- household chemicals, gasoline, oil, pesticides, antifreeze, paint, and high amounts of anti-bacterial soaps and detergents.

Don’t strain your drain. 

The less water you use, the less your septic system has to work. Stagger the use of water-based appliances, use high-efficiency plumbing fixtures, and repair any leaks in your home.