There’s an older home in the neighborhood that was occupied by a single woman for more than two decades. When she died of cancer a few years ago, her son inherited the home and moved in. Not long after, the septic system failed and had to be replaced.

Eric Knopf, owner of Indigo Designs Inc., a company that designs and maintains septic systems, said that septic systems definitely have a life span. "You can get about 30 years on a home’s roof. Some cars will get you 200,000 miles; some maybe 300,000. Septic systems also have a definite life span."

According to the Environmental Protection Agency, an estimated 30 percent of all households use a soil-absorption septic system to dispose of waste. A properly designed, installed and maintained septic system is comprised of a watertight container, drain field, and adequate soil conditions beneath the drain field.

Only 32 percent of all septic systems in existence meet the criteria for adequate soil absorption, due to the presence of bedrock, sandy soil and high water tables.

Here’s the quick scoop on what happens in an on-site septic system — i.e., the sewage treatment a home needs if not hooked in to a community sewer:

Wastewater leaves the house and enters the septic tank. The septic tank acts as a holding tank and allows the solids to settle. The heavier solids sink to the bottom forming the sludge layer; the lighter solids — fats, oils and grease — rise to the surface and form the scum layer.

The relatively clear layer in the middle is called effluent. While this is going on, naturally occurring anaerobic bacteria begin breaking down the solids in size and destroying the pathogens, or germs.

As the effluent enters the drain field, it percolates through the gravel bed where a large portion of the pathogens are destroyed. Pockets of oxygen created by the uneven shape of the gravel allow the more efficient aerobic bacteria to exist. As the effluent exits the drain field, the natural soil completes the treatment process.

By the time the effluent has traveled 2-3 feet through the soil, all the remaining pathogens have been destroyed.

"What happens in a septic tank is a beautiful thing," Knopf said. "You have all these little critters working together. When you introduce something that kills what they are doing, it disrupts the process — at least for a while. What’s going on in there is fairly robust and will come back."

Jim vonMeier, who operates, advises homeowners to have their septic contractor inspect the system in the beginning to get a benchmark of how the system is operating because they can tell when a system is "cooking" properly.

Medications are one potential disruptor to septic system processes. "The drugs people take can have a negative impact on a septic system," vonMeier said.

"Antibiotics, for example … kill bacteria in your body, but that killing process does not stop there. When you go to the bathroom, you are flushing those antibiotics out to your septic system, where they kill the ‘good’ bacteria in the tank and soil. Chemotherapy drugs can also have the same effect."

States and counties have different rules and regulations regarding on-site septic systems. For example, Washington’s Kitsap County requires that all developed property utilizing an on-site sewage system have the system inspected and evaluated through the Kitsap County Health District prior to conveying the property to a new owner. New homes and businesses that have never been occupied are exempt.

"It’s common to hear that the best solution to pollution is dilution," Knopf said. "While systems do recover, they are not designed to take everything we give them. For example, in Washington state, kidney dialysis patients are allowed to install a small drain field just for that use. It just depends where you are and what you are dealing with."

Show Comments Hide Comments


Sign up for Inman’s Morning Headlines
What you need to know to start your day with all the latest industry developments
Thank you for subscribing to Morning Headlines.
Back to top
Log in
If you created your account with Google or Facebook
Don't have an account?
Forgot your password?
No Problem

Simply enter the email address you used to create your account and click "Reset Password". You will receive additional instructions via email.

Forgot your username? If so please contact customer support at (510) 658-9252

Password Reset Confirmation

Password Reset Instructions have been sent to

Subscribe to The Weekender
Get the week's leading headlines delivered straight to your inbox.
Top headlines from around the real estate industry. Breaking news as it happens.
15 stories covering tech, special reports, video and opinion.
Unique features from hacker profiles to portal watch and video interviews.
Unique features from hacker profiles to portal watch and video interviews.
It looks like you’re already a Select Member!
To subscribe to exclusive newsletters, visit your email preferences in the account settings.
Up-to-the-minute news and interviews in your inbox, ticket discounts for Inman events and more
1-Step CheckoutPay with a credit card
By continuing, you agree to Inman’s Terms of Use and Privacy Policy.

You will be charged . Your subscription will automatically renew for on . For more details on our payment terms and how to cancel, click here.

Interested in a group subscription?
Finish setting up your subscription