Basement floor drain is backing up

Symptoms

• Water or sewage comes up out of the floor drain
• Backup happens when a toilet flushes or washing machine drains
• Basement floor near the drain is wet or smells bad
• May happen more during heavy rain

Likely causes

• CommonMain sewer line blockageSince the floor drain sits at the lowest point, it's often the first place backed-up water appears.
• CommonTree roots in the sewer lineA frequent cause of recurring backups, especially in older homes.
• PossibleHeavy rain overwhelming a combined or aging sewer systemSome older systems can back up during storms.
• Less commonFailed sump pump if the drain is tied to sump dischargeLess common but possible depending on the plumbing layout.

What to do

1. Stop using water-consuming fixtures (washing machine, dishwasher, showers) immediately to avoid adding to the backup.
2. If sewage is visibly present, avoid direct contact and keep pets and children away from the area.
3. Check whether the backup correlates with using another fixture, which points strongly to a main line issue rather than something local to the drain.
4. Note if backups happen more during or after heavy rain, which is useful information for a plumber.
5. Do not attempt to snake a suspected main line clog yourself; this needs a motorized main line snake or camera inspection.
6. Contact a plumber promptly, especially if sewage is present, since this is both a plumbing and a basic hygiene concern.

When to call a pro

Call a plumber promptly for a floor drain backup involving sewage or that correlates with using other fixtures, since it typically points to a main line issue.

Safety