Washing Machine Drain Overflowing

What to Do Right Now

1. Stop the washer. Pause the cycle or turn the dial to off.
2. Close the hot and cold supply valves behind the machine so it cannot keep filling.
3. Keep water away from electrical outlets and cords. Unplug the washer only if the plug is dry and you can reach it safely.
4. Mop up so water does not seep into a floor, carpet or crawlspace below.
5. Hold off on laundry until you know why it overflowed.

The water that comes out of a washer's drain is soapy gray water, and if it backed up from the main line it can be worse than that. Wear gloves and wash your hands afterward.

Why a Washer Drain Overflows

A washing machine empties fast. The pump pushes a large volume of water into a standpipe, which is the vertical pipe with a bend at the bottom called a trap, and then into the house drain. The pipe is only about as wide as it needs to be for normal flow. If a clog has narrowed the pipe, the washer sends water faster than the pipe can carry it, and it comes up out of the standpipe.

Lint is the usual culprit. Fibers wash out of clothes, mix with soap and grease, and coat the inside of the trap and drain line. Over months it thickens into a plug. A hose that was pushed all the way down the standpipe can also make it worse, because it can seal off the air the drain needs.

Standpipe, Hose and Fit

• Standpipe height. The top of the pipe has to be high enough that water does not siphon out of the washer on its own, and the pipe must not be so low that water spills over the top. A standpipe that is too short overflows more easily. Local plumbing code sets the exact height range for your area, so ask a plumber rather than guessing.
• Hose pushed in too far. The drain hose should hang loosely in the top of the standpipe, not be shoved down it or sealed with tape. A tight seal stops air from entering and slows the drain.
• Hose kinks. A kinked hose can make the pump struggle, though it more often causes the washer to stop than to overflow.

Is It the Main Line?

The washer is often the first thing to show a main line problem, because it moves the most water at once. Watch for these signs while the washer drains:

• A toilet or shower nearby gurgles or bubbles. See gurgling drains.
• Water rises in a tub or floor drain, especially in a basement.
• Several fixtures drain slowly, not just the washer.
• You smell sewage in the laundry area. See sewage smell in the house.

If you see any of those, do not run the washer again. The signs of a clogged main sewer line are covered in our guide, and a toilet that rises is covered under toilet backing up.

What You Can Safely Try

1. Pull the drain hose out of the standpipe and check for lint on the end.
2. Look down the standpipe with a flashlight. Pull out any lint you can see with a gloved hand or a plastic drain tool.
3. Pour a bucket of warm water into the standpipe and watch. If it drains steadily, the blockage was local. If it rises, it is not.
4. Rinse the lint trap or filter if your washer has one.

Do not use chemical drain cleaner. It sits in a trap that is already holding water, it can splash, and it is hard on pipes. Ryan clears drains mechanically, by hand and with the right tool for the pipe.

Washer Water and Septic Tanks

A washer sends a lot of water to a septic system in a short time. The EPA advises septic owners to spread laundry across the week, because doing it all in one day can harm the system. If your washer overflows on a home with septic, other drains are slow, or you smell sewage, the tank or drainfield may be full. Ryan does septic system repair. If the tank needs pumping, that is a job for a septic pumping company.

Laundry Rooms in Mountain Homes

Washers in these homes often sit in a basement, a utility room off the garage, or a closet over a crawlspace. A basement washer drains toward a main line that may be low, long and lightly sloped. A laundry room over a crawlspace may hide a leak for days. If water got beneath the floor, tell Ryan so he can look at the pipes underneath.

When to Call Ryan

• The standpipe overflows again after you cleared the lint.
• Other fixtures gurgle, back up or drain slowly when the washer runs.
• Water came up through a floor drain or a toilet.
• You are not sure the standpipe or trap was installed correctly.

Ryan clears the blockage, finds out whether it is the standpipe, the branch or the main, and tells you what he sees. The estimate is free, there is no trip fee and no diagnostic fee, and you know the price before any work starts. See drain cleaning for what that covers.