Symptoms
- Water or sewage rising from the floor drain
- Backup happens when running the washing machine, toilet, or during heavy rain
- Foul odor accompanying the backup
Likely causes
- CommonClogged main sewer lineGrease, roots, or debris can block the line so water backs up at the lowest point, often the floor drain.
- CommonOverwhelmed municipal storm or combined sewer system in heavy rainDuring major storms, city systems can back up into connected homes.
- PossibleFailed or missing backwater valveWithout a check valve, sewage can flow backward into the house under pressure.
What to do
- Avoid running water, flushing toilets, or using the washing machine until the backup is resolved, since that adds more volume to the clog.
- Treat any backup water as contaminated with sewage and avoid direct contact; wear gloves and boots if you must be near it.
- Check if the backup coincides with heavy rain (suggesting a municipal or storm issue) or happens regardless of weather (suggesting a private line clog).
- Do not attempt to snake a main sewer line yourself unless experienced, since it requires the right equipment.
- Ventilate the area and consider a wet/dry vacuum rated for water, not sewage, disposing of contaminated water per local guidance.
- Call a plumber to clear the clog and inspect the line with a camera if backups are recurring.
- Ask about installing a backwater valve to prevent future sewage backups if the home doesn't have one.
Tools and parts
- Rubber gloves
- Boots
Backwater valveSearch: “sewer backwater valve”
When to call a pro
Call a plumber promptly for a sewer line backup, and a water damage restoration company if sewage has contaminated the area.
Safety
Use caution
Sewage backup can carry bacteria and contamination; avoid direct contact and ventilate the area, and call a professional for cleanup if it's a significant sewage event.