What to do if Your Sewer Backs Up

Immediate Actions

  • Sewer backup informationCall the City at 503-618-2626 (regular business hours) or 503-661-3906 (evenings, weekends or holidays).
  • If sewage is flowing from floor drains, toilets, sinks, etc., place rags over the backup and anchor in place with a sandbag or cat litter bag to reduce the flow.
  • Thoroughly wash any part of your body that comes in contact with sewage.
  • Evacuate all people and pets. Contact with sewage can be harmful to humans and animals.

The City will immediately respond to the situation and provide a limited, preliminary clean-up of the backup to protect public health. We will also provide information regarding the responsibility for clean-up and costs.

Gresham wastewater customers are responsible for sewer backups caused in their private sewer lines. If the blockage is within the public sewer system, clean-up will be provided by a private service provider.

Follow-up Steps

  • Contact your homeowners' insurance agent to determine if any losses are covered by your policy.
  • Arrange for clean-up if the City determines that the backup is your responsibility.
  • Assess damage. Itemize and document damage to your property.


  • Never pour food grease down the kitchen sink or toilet.
  • Do not dispose wipes or other garbage in the toilet.
  • Install a backwater valve if needed. If your property's lowest drain elevation in your home or building is below the rim (typically the street) of the nearest upstream sewer manhole cover, your property may be at risk of a backup. Call Community Development for more information at 503-618-2845.
  • Maintain and inspect the backwater valve as recommended by manufacturer.
  • Maintain insurance coverage to cover damage caused by sewage backflow incidents.