A building's drains carry wastewater from fixtures through traps and drain pipes to the building drain, and from there through the building sewer to a municipal sewer or septic system.[1][2] Blockages from grease, wipes and tree roots can cause clogs and sewer backups, which damage property and threaten health.[3][4]
Drain, waste and vent system
Every fixture must have a trap, which holds a water seal that keeps sewer gas out of the building, and vents let air into the system, usually through a stack that passes through the roof.[1] The building drain is the lowest horizontal part of the drainage system, and the building sewer carries wastewater from it to the public sewer. Cleanouts, openings for clearing blockages, are installed at the start of the building sewer and at the base of each stack.[1]
What not to flush or pour
The EPA urges people to flush only toilet paper, warning that wipes, including disinfecting wipes, can damage household plumbing, sewers and septic systems.[5] Fats, oils and grease (FOG), including cooking oil, dairy products, mayonnaise and salad dressings, are liquid when hot but harden in pipes. The Cherokee County Water and Sewerage Authority says running hot water with grease does not help, and advises pouring grease into a container for the trash and using sink strainers; grease buildup can back sewage up into homes or cause overflows into waterways.[6]
Sewer overflows and backups
The EPA estimates that at least 23,000 to 75,000 sanitary sewer overflows occur in the United States each year, not counting backups into buildings; causes include blockages, line breaks, groundwater or stormwater entering the system, power failures and poor design.[3] The Insurance Information Institute notes that homeowners generally own and maintain the sewer lateral from the city main to the house, and names aging sewers, tree roots and grease as common causes of backups.[4]
A backwater prevention valve lets sewage flow out of a house but not back in.[4] FEMA advises having a licensed plumber install backflow valves on pipes entering a building to keep floodwater and sewage from coming up through drains.[7] Sewer backup coverage is available from most insurers as an addition to a homeowners policy.[4]
Septic systems
More than one in five U.S. households use septic systems, mostly in suburban and rural areas without public sewers. Solids settle in the tank, and the soil of the drainfield treats the wastewater.[2] The EPA recommends having a professional inspect a household system at least every three years and pumping the tank typically every three to five years, and advises keeping vehicles off the drainfield.[8] Signs of a failing system include sewage backing up into the home, slow or gurgling drains, odors, and wet spots or unusually lush grass over the drainfield.[9] In Cherokee County, septic system owners are referred to North Georgia Environmental Health.[10]
References
- ^ ^ ^ "Drain, Waste, and Venting". Building Maintenance & Construction, University of Hawaiʻi Maui College. pressbooks.oer.hawaii.edu
- ^ ^ "About Septic Systems". U.S. Environmental Protection Agency, updated July 7, 2026. epa.gov
- ^ ^ "Sanitary Sewer Overflows". U.S. Environmental Protection Agency, updated April 13, 2026. epa.gov
- ^ ^ ^ ^ "Protect your house from sewer backups". Insurance Information Institute. iii.org
- ^ "EPA Encourages Americans to Only Flush Toilet Paper". U.S. Environmental Protection Agency, March 30, 2020. epa.gov
- ^ "Fats, Oils & Grease (FOG)". Cherokee County Water and Sewerage Authority. ccwsa.com
- ^ "Protect Your Home from Future Flooding". Federal Emergency Management Agency, July 18, 2018. fema.gov
- ^ "How to Care for Your Septic System". U.S. Environmental Protection Agency, updated August 17, 2026. epa.gov
- ^ "Frequent Questions on Septic Systems". U.S. Environmental Protection Agency, updated March 11, 2026. epa.gov
- ^ "Septic System & Stormwater Information". Cherokee County, Georgia. cherokeecountyga.gov