What to do right away
- Stop all water use in the building, including fixtures that appear to drain normally. Their discharge can reappear at the lowest open drain.
- Close doors or use a visible barrier to keep children, pets, and visitors out. Do not walk through sewage to retrieve belongings.
- If electrical devices or outlets are in the wet area, do not touch them or enter the water. Tell emergency responders or an electrician about the contaminated water before power is addressed. [1] [2]
- Call for plumbing help and describe every affected drain, where the overflow appeared first, what the wastewater looks like, and whether nearby properties also seem affected.
Wastewater seeks the lowest available opening when it cannot continue downstream. A floor drain, basement shower, tub, or low toilet may overflow even though the obstruction is in a larger shared pipe beyond that fixture.
One backed-up fixture can point to its local branch. Several fixtures backing up together, or a toilet discharge appearing in a tub, points farther downstream. Report the pattern rather than opening a cleanout, which may release sewage under pressure.
What to note from a clean area
- Time the backup began and which fixture was in use.
- All drains that rose, gurgled, or stopped draining.
- Photos taken from outside the contaminated area and the time of each call for help.
- Any prior cleaning, camera inspection, root treatment, or sewer repair.
- Seattle Public Utilities advises documenting damage and keeping cleanup invoices after a sewer backup. [2]
The first steps are the same, but the cause may be in a fixture branch, the home’s sewer line, a public sewer, or an onsite septic system. If the private line is open and a public problem is suspected, the serving wastewater utility may need to investigate. [2]
Do not open a cleanout to find out. It may release sewage under pressure. Let the plumber choose a safe access point, and keep photos taken from clean areas along with the time of each call and any cleanup invoices. [2]
When the plumber arrives, explain which drain rose first and what other fixtures were doing at the time. The plumber can use that pattern to decide where to begin checking the drain instead of sending more water through every fixture.
Once the blockage is cleared, the affected area may still need separate cleanup. Ask which fixtures can be used, which should remain off, and whether any contaminated materials need attention before people or pets return. Keep the plumbing test limited to the fixture the plumber requests.