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Sewage spill in house

Sewage spills are most often caused by clogged or broken pipes belonging to private owners. On rare occasions, problems in pipes owned by local sewer agencies or the county can result in sewage spills on private property—refer to the report a problem page for guidance to contact your local sewer agency or King County.

For sewage complaint investigations relating to septic systems, please contact the Public Health Wastewater Program.

The King County Wastewater Treatment Division recommends taking the following steps in the event of a sewage spill in your home:

Sewage contains disease-causing contaminants that can require extensive clean up and restoration.          Sewage contains disease-causing contaminants that can require extensive clean up and restoration. 

Evacuate if necessary. If the flooded area can not be isolated, children under two years old, adults over the age of 60, and anyone suffering from respiratory ailments—including allergies—or weakened immune systems should leave the premises.

Stay out of flooded areas. Entering a flooded area creates a risk for accidental electric shock, excessive exposure to disease-causing contaminants, and potential injury from rushing water.

Safely turn off electricity in affected areas. To prevent accidental electrical shock, turn off circuit breakers and unplug electrical appliances in affected areas. Do not attempt if you must stand in or make contact with water to do so.

Contact your doctor at the first sign of adverse health effects.

Stop using plumbing and appliances that drain into the sewer system, including sinks, showers, toilets, dishwashers, and laundry machines.

Avoid direct contact with sewage and sewage contaminated items.
  • Wear rubber gloves and boots when in the vicinity of the back up. Remove boots and gloves before returning to unaffected areas.
  • Wash hands thoroughly after handling any contaminated items.
Prevent the spread of contaminants and odors.
  • Turn off forced air furnaces and air conditioners.
  • Cover or close vents capable of spreading contaminants and odors.
  • Do not use wet/dry vacuums because of the danger of electrical shock and the spread of aerosolized germs by the fan motor.
  • Be careful not to track contamination into other parts of the residence.

Contact your insurer and your local sewer district immediately. Know in advance what insurance coverage you have for sewer backups. Most sewage spills are due to blockages in a building's side sewer, which is private property. Your insurer and local sewer district can help you determine the appropriate course of action.

Consider hiring a professional water damage restoration service. If there is too much water to absorb using mops and sponges, professional water damage restoration experts can be found in the Yellow Pages under "water damage restoration."

King County is ready to assist you. On rare occasions when the regional conveyance system contributes to a residential sewage spill, emergency cleanup support is available. If you have questions about a sewage spill you believe is related to the regional conveyance system, call King County's wastewater emergency hotlines:
  •  206-263-3801 (Seattle, Lake Forest Park, Kenmore, and Shoreline)
  •  206-263-1760 (all other areas in the service area)
Wear rubber boots and gloves.
  • Disinfect all mops, sponges, and brushes.
  • Launder clothes worn during cleaning separately from other laundry.
Clean and disinfect contaminated surfaces.
  • Plumbing fixtures and vinyl, metal, wood, and concrete surfaces should be cleaned thoroughly with hot water and a mild detergent, such as dish detergent, and then disinfected with bleach solution.
  • Mix one part of liquid household bleach with 10 parts water (1:10). Dampen contaminated surfaces and allow them to air dry.
Remove and discard porous materials.
  • Upholstered furniture, loose rugs, and drapery cannot be salvaged and must be discarded properly.
  • Remove and replace lath, plaster, plasterboard, and drywall saturated to the point of being soft to the touch.
  • Wall-to-wall carpeting and pad cannot be reliably disinfected and must be removed and sent to a local transfer station.


The Washington State Department of Health's guidance for cleaning up a sewage spill  is also available in Spanish, Chinese, Korean, Russian, and Vietnamese.

Keep yourself safe during a flooding event or sewage overflowDownload print version 

Sewage Overflow Card, front sideKnow Your sewer system—know who to call. Download this fact sheet and record emergency contact numbers in case of a sewage overflow. The back side of this fact sheet includes information on keeping yourself safe during a flooding event or sewage overflow and helpful hints to prevent overflows.