Septic Systems

AKA Onsite Wastewater Treatment Systems

Homeowners who do not have access to public sewers rely upon on-site wastewater treatment systems, more commonly called septic systems, to treat their household wastewater. Septic systems can be very effective at reducing pollutants if they are installed and maintained properly. When not properly installed and maintained, septic systems are one of the biggest potential sources of pollution present on residential properties.

Improperly functioning systems release wastewater into the environment, which can then contaminate groundwater and wells with harmful bacteria and viruses, surface in the property creating a public health hazard, pollute streams and lakes, and release phosphorus that triggers excessive aquatic plant growth and algae blooms.

How Does a Conventional System Work?

A traditional septic system consists of a tank, a distribution box and a soil absorption or "leach" field. Wastewater flows from the house into the septic tank. Here the heavy solids settle out and are partially decomposed by bacteria to form sludge at the bottom of the tank. Light solids and grease form a floating scum layer at the top of the tank. Liquid wastewater flows out of the tank and into the distribution box, where it is discharged through perforated pipes into the soil absorption field. It is here in the soil that the bulk of the wastewater is "cleaned" before it is released into the environment. Microorganisms and natural bacteria that live in the soil feed upon and digest the waste as it filters through the soil, and are the workforce behind the whole process. Special Note: It is very important that no solids leave the tank. It is the job of the tank to store solids until they can be pumped out! *The average systems needs to have the septic tank pumped every 3-5 years, depending on usage.*

Proper Use and Maintenance

To prevent the release of harmful pathogens and bacteria into the environment, it is important to maintain a properly functioning septic system. An inadequate or failing system can be a health hazard to your family, community and the environment. Untreated wastewater can move through the ground and contaminate groundwater supplies, wells, streams, rivers and lakes. The proper use and regular maintenance of your system can not only help ensure your system is working as well as possible, but it can also save you from the costly expenses and headaches associated with correcting a failing system.

Have your system pumped and inspected regularly. (*The average is every 3-5 years)

Conserve water in your home.

Redirect surface water flow away from your soil absorption field.

Plant only grass above your system.

Avoid septic system additives.

Consider replacing or updating old systems before problems arise. (* The lifespan of an average septic system is 15-30 years.)

Never use your toilet or drains for the disposal of fats, grease, paper towels, diapers, disinfectants, cleaning product or household hazardous wastes.

To download fact sheets about septic system technologies, record keeping forms, or
troubleshooting procedures, visit the Water Publications Page.

Alternative Technologies

In recent years, a variety of new technologies have been developed to provide superior wastewater treatment. Many "alternative" septic systems offer advanced treatment by means of providing both primary and secondary stages of waste digestion. Unlike the traditional system where the majority of treatment occurs in the soil absorption field, many alternative technologies provide a media chamber for microorganisms to perform "pre-treatment" prior to the wastewater being released into the soil. Media chambers may use peat, sand, electronic aerators, or timed-dosing devices. While most of the advanced systems are not gravity-fed like the traditional system and may require electricity to operate pumps, they have allowed better wastewater treatment to occur in situations that commonly present problems: sites with poor soils, high water tables, shallow depth to bedrock, and inadequate space or setbacks from streams and shorelines. For more information, take a look at the alternative onsite wastewater system fact sheets on the Water Publications Page.

Additional Resources

"A Homeowner's Guide to Septic Systems" EPA Booklet. Download as pdf.

"Household Chemicals and Your Septic System" Fact Sheet. Download as pdf.