Basement Floor Drain Backing Up: What to Do

What are the 4 causes of a basement floor drain backing up?

The 4 causes of a basement floor drain backing up are listed below.

• A main sewer line clog from roots, grease or wipes blocks the flow.
• A collapsed or sagging sewer pipe holds waste.
• Heavy rain overloads the sewer system.
• A failed backwater valve lets the public sewer push back into the house.

Is a basement floor drain backing up an emergency?

Yes, a basement floor drain backing up is an emergency, because sewage in the house is a health hazard and the backup grows with every drain used.

What should you do first when the floor drain backs up?

The 4 things you should do first when the floor drain backs up are listed below.

1. Stop using all sinks, toilets, showers and the washer.
2. Keep people and pets away from the water.
3. Move stored items off the floor.
4. Call a plumber for emergency main line clearing.

When should you call a plumber?

You should call a plumber in the 4 situations below.

• Sewage rises from the floor drain.
• Every drain in the house runs slow.
• The backup returns after rain.
• The main cleanout overflows.

Related plumbing problems and next steps

How much does the plumbing repair cost?

The plumbing repair cost depends on the clog: main sewer line clearing costs $100–$800, according to HomeAdvisor. Sewer backup prices and local plumbers are on the sewer backup in Lancaster page.

What is a related plumbing problem?

A related plumbing problem is main sewer line clogged symptoms, and the main sewer line clogged symptoms guide lists its causes and first steps.

Written and fact-checked by the Lancaster PA Plumbers editorial team using HomeAdvisor, EPA WaterSense and City of Lancaster data. Last updated October 29, 2026.