Sewage is backing up in my basement — what do I do?

Why does stopping all water use matter so much?

Because the main line is blocked and the lowest opening in the house is the relief point. That is almost always the basement floor drain or a basement shower pan. The washing machine draining upstairs will push water out onto your basement floor even though nothing in the basement is running.

Tell everyone in the house. A single flush while you are on the phone with us undoes the whole effort.

Is it one fixture or the main line?

If one fixture is slow and everything else drains fine, the problem is in that branch. If several fixtures are slow, if water comes up somewhere when you use something else, or if it is showing at the floor drain, the problem is in the main.

The tell we trust most: a gurgle from the toilet or the floor drain when the washing machine dumps. A washer discharges a lot of water very fast, so a partially blocked main announces itself there before it announces itself anywhere else. If you hear that, you have a main-line problem and some time to deal with it before it becomes a cleanup.

Is the backup safe to clean up yourself?

Gray water from a laundry backup is one thing. Sewage is another. It carries bacteria, and it soaks into anything porous it touches. Boots, gloves, eye protection, and nothing porous goes back in the house.

If it covers a large area or it has soaked into finished flooring or drywall, this is a restoration job, not a mop job, and it is worth calling your insurance carrier the same day.

Why did it happen?

In the older river-city neighborhoods — Anoka, Robbinsdale, Crystal, Osseo, north Minneapolis — it is usually roots in a clay tile lateral, and it repeats until the pipe is dealt with. In newer construction it is far more often grease, wipes, or a belly in the line.

Whatever the cause, we camera it after the line is open. Clearing a main line without ever looking at it is how the same backup happens again in eight months.

Related questions

Why does my toilet gurgle when the washing machine drains?

It means the main line is partially blocked. The washer discharges fast, air gets pushed back through the nearest trap, and you hear it at the toilet. It is an early warning of a backup, not a quirk.

Who is responsible for the sewer lateral?

In most metro cities the homeowner owns the lateral from the house to the connection at the city main, including the portion under the street. Rules vary — confirm with your municipality.

Does homeowners insurance cover a sewage backup?

Standard policies frequently exclude sewer and drain backup unless a specific backup endorsement was added. Read your policy or call your agent. We are plumbers, not insurance advisors.