USA Expert Plumbing

Water coming up through the floor drain

By USA Expert Plumbing Editorial Team. Updated . 1 min read.

Short answer

Water coming up through a floor drain usually means a clog or backup further down the main line, so water from other fixtures has nowhere to go. Stop using water in the house, check whether it is clear water or sewage, and call a plumber to clear the line. During heavy rain, an overloaded city sewer can also push water up.

In this guide
  1. What to do right away
  2. Common causes
  3. How it is fixed
  4. Prevention
  5. Clear water vs sewage
  6. Heavy rain backups
  7. Questions to ask

A basement floor drain is usually the lowest drain in the house. When the main line downstream is blocked, water from sinks, showers, toilets and the washer backs up there first.

What to do right away

  1. Stop using water: no flushing, laundry, dishwasher or showers.
  2. Check what is coming up. Sewage means a sewer backup; see our sewer backup in the basement guide.
  3. Keep people and pets away and avoid contact with dirty water.
  4. Photograph it for insurance.

Common causes

ClueLikely cause
Water rises when the washer drainsClog in the main line or the floor drain branch
Water rises when toilets upstairs flushMain sewer line blockage
Only during heavy rainCity sewer surcharge or groundwater through the drain
Recurring every few monthsRoots, a sagging line or grease buildup

How it is fixed

A plumber snakes or hydro jets the line from a cleanout. If the problem keeps coming back, a camera inspection shows roots, breaks or sags. See our drain cleaning cost, hydro jetting cost and sewer camera inspection cost guides.

Prevention

  • Keep grease, wipes and lint out of drains.
  • Add a lint trap to the washer discharge if it empties into a laundry sink or floor drain.
  • Ask about a backwater valve if backups happen during storms.

Clear water vs sewage

Clear or slightly cloudy water usually comes from sinks, the washer or groundwater, and is less hazardous. Gray water with debris, or anything with a sewage smell, means the main sewer line is backing up. Treat it as contaminated: avoid contact, keep children and pets away and disinfect afterward.

Heavy rain backups

If the drain only backs up during storms, the city sewer or storm system may be overloaded, or groundwater may be pushing up through the drain. A plumber can install a backwater valve or a floor drain plug with a check valve. Some cities offer rebates for backwater valves.

Questions to ask

  • Where was the blockage, and can I see camera footage?
  • Does the house have an accessible cleanout?
  • Would regular jetting or root treatment prevent repeats?

Common questions

Why does my floor drain back up when I do laundry?

The washer sends a lot of water quickly. If the main line is partly clogged, it backs up at the lowest drain.

Can I use chemical drain cleaner on a floor drain?

It rarely clears main line clogs and can make a plumber's job riskier. Call a plumber instead.

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