Laundry and Floor Drain Backups: Causes and First Steps

Why the laundry is an early warning

A washer's drain pump pushes water into a standpipe or laundry sink much faster than a bathroom sink ever drains. If the standpipe, its trap or the line beyond it is partly blocked, the water has nowhere to go and overflows the top of the pipe, often mid-cycle.

Lint, fabric fibers, small socks and sediment build up in laundry lines over time. In many older Anaheim homes the laundry is in the garage or a side room, sometimes with a floor drain nearby that also ties into the main line. When the main is blocked, the washer's discharge can come up through that floor drain instead.

What the backup is telling you

IfThe standpipe overflows only during the drain cycle, and other drains are fineThenA clog in the standpipe, its trap or the laundry branch line.
IfWater comes up through a nearby floor drain when the washer drainsThenThe line beyond both is blocked; often the main line.
IfThe tub or toilet gurgles while the washer drainsThenA partial main line blockage or a venting issue.
IfWater appears behind the washer but the drain is clearThenCheck the drain hose connection and the supply hoses for a leak.

First steps

Stop the washer.Pause or cancel the cycle so the pump stops sending water.
Check the washer's own filter.Many front-loaders have a pump filter behind a small panel. Clean it per the manual, with towels ready.
Look at the drain hose.Make sure it is not kinked and is not jammed so far into the standpipe that it seals the opening.
Watch other drains.Run a sink for a moment. If floor drains or the tub react, treat it as a main line problem.
Call if water keeps coming up.A laundry branch or main line clog needs a cable from a cleanout or the standpipe.

Preventing laundry line clogs

Use a lint trap or mesh filter on the end of the drain hose or in the laundry sink.
Empty pockets before washing.
Wash small items in a mesh bag.
Clean the washer's pump filter as the manufacturer recommends.
Spread large loads out instead of running several back to back if the drain seems slow.

Terms

Standpipe: The vertical pipe a washer drain hose hangs into; it has its own trap below.
Laundry tub: A deep utility sink the washer may drain into instead of a standpipe.
Floor drain: A drain set in the floor of a garage, laundry or utility area; usually one of the lowest openings in the system.
Trap primer: A device that keeps water in a rarely used floor drain trap so sewer gas stays out.

Common questions

Why does my floor drain smell?

Floor drains are rarely used, so their trap water evaporates and lets sewer gas through. Pouring a bucket of water in it usually solves the smell.

Can a washing machine cause a main line clog?

It rarely causes one on its own, but lint and heavy volume can add to an existing partial blockage and make it obvious.

Is it safe to keep doing laundry if the drain is slow?

It is better to pause. Each load can overflow the standpipe or push water up through floor drains.

General information for Anaheim, not a quote or professional advice. In an emergency, call 911.