Why Does My Washing Machine Standpipe Overflow? Causes and Fixes

If the standpipe only started overflowing recently, a clog is the most likely cause. If it has overflowed since the washer was installed, look at the setup first.

Graphic: summary of this guide, made by our team from the cited sources.

Causes at a glance

Clue	Likely cause	Fix
Overflow started recently, gets worse	Lint or grease clog in the trap or line	Snake the standpipe and line
Water comes up in a nearby sink too	Clog in a shared drain line	Snake the shared line
Hose jammed tight or deep in the pipe	Hose sealed or pushed in too far	Pull the hose up, leave an air gap
Standpipe shorter than about 18 inches above the trap	Not enough height to hold a surge	Plumber to extend it
New high-capacity washer, old narrow pipe	Pipe can't carry the pump rate	Plumber to check pipe size
Floor drain and toilets back up too	Main drain or sewer problem	Plumber or city sewer department

Sources: pump rate and hose depth from GE Appliances; standpipe height from ICC IPC Chapter 8.

First, make sure it really is the standpipe

Water on the laundry room floor does not always come from the drain. Watch a full cycle, especially the drain and spin, with a flashlight.

• Water rises and spills out of the top of the standpipe while the washer pumps out: it is a drain problem. Keep reading.
• Water appears at the front left corner of a top-load washer: GE says that is usually the washer's own overflow tube, and in most cases it is caused by too many suds pushing water over the inner basket (GE Appliances).
• Water drips from the hose connections on the back: a loose or worn fill or drain hose, not the standpipe.

Too many suds

Oversudsing causes leaks that look like drain trouble. GE recommends HE detergent, which is low-sudsing, in all its washers, and warns that too much detergent leads to over-sudsing and residue (GE Appliances). Over-sudsing is especially common in homes with water softeners (GE Appliances).

GE's test for too much detergent: put a washed but not yet dried washcloth in a bowl of hot water. A white film on the water means you are using too much (GE Appliances). Towels, sweaters and blankets can hold soap over time, so GE suggests washing them occasionally with no detergent (GE Appliances).

Check the hose first

GE says the standpipe or wall drain must be open to the atmosphere, and that the hose should go no more than 5 inches into the pipe for its top-load washers and 7 inches for front-loaders (GE Appliances). A hose stuffed deep and wrapped with tape to stop splashing seals the pipe, so the water can't drain freely. Amana's front-load installation checklist is stricter: no more than 4.5 inches (113 mm) into the drainpipe, and it says plainly not to seal the hose into the pipe with tape (Amana). Pull the hose up, secure it with the clip or strap that came with the washer, and test.

Clear the clog

Lint from clothes, soap residue and, in shared lines, kitchen grease build up in the standpipe's trap and the line beyond it.

1. Unplug the washer and pull it out so you can reach the standpipe.
2. Pull the drain hose out and bail or sponge out the standing water.
3. Feed a drain auger down the standpipe, through the trap and into the line. Turn as you push; pull out the lint you hook.
4. Pour a bucket of water down the standpipe. It should drain quickly without backing up.
5. Put the hose back and run a rinse-and-spin cycle with no clothes, watching the standpipe.

Some people add a mesh lint catcher to the end of the drain hose. If you do, empty it often, because a full one can slow the flow.

Check the standpipe itself

The International Plumbing Code requires each standpipe to have its own trap and to extend at least 18 inches and no more than 42 inches above the trap weir, with access for cleaning (ICC IPC Chapter 8). Washer makers also set their own minimum heights. GE says the drain must be at least 30 inches above the floor for its top-load washers and at least 24 inches for front-loaders, and no more than 8 feet, and that the standpipe must have an inside diameter of at least 1 1/2 inches (GE Appliances). Amana's front-load checklist lists a minimum standpipe height of 39 inches (Amana). Check your own washer's installation manual; models differ.

A standpipe that's too short has too little volume to absorb the surge. Too low a drain can also cause siphoning, where the washer fills and drains at the same time, GE notes (GE Appliances). Changing standpipe height or size is a job for a plumber, and may need a permit where you live.

Standpipe numbers in one place

Requirement	Number	Source
Height of standpipe above its trap weir	At least 18 inches, no more than 42 inches	ICC IPC Chapter 8
GE top-load drain height above the floor	At least 30 inches, under 8 feet	GE Appliances
GE front-load drain height above the floor	At least 24 inches, under 8 feet	GE Appliances
Standpipe inside diameter	At least 1 1/2 inches	GE Appliances
GE drain hose outside diameter	About 1 1/4 inches	GE Appliances
Hose depth into the pipe	No more than 5 inches (top-load) or 7 inches (front-load)	GE Appliances
Amana front-load hose depth and standpipe height	No more than 4.5 inches in; standpipe at least 39 inches	Amana

The height of the drain also changes how fast the washer empties. GE says flow drops by about 1 gallon per minute for each extra foot of drain height (GE Appliances). So a taller drain slightly slows the pump's discharge.

GE does not recommend check valves on the drain hose, because they can restrict flow (GE Appliances). If someone added one to stop backflow, it could be part of your problem.

If the washer drains into a laundry sink

GE says a washer can drain into a standpipe, a wall drain or a laundry tub (GE Appliances). With a laundry tub, the tub's own drain and trap have to keep up with the pump. If the tub fills up and overflows, clean the strainer, then snake the tub drain the same way as a standpipe. A mesh lint catcher on the hose end helps here too.

When the problem is further down

If washer water shows up in the kitchen sink, see Why Does My Washing Machine Drain Into My Kitchen Sink? If several fixtures back up at once, the City of Minneapolis says most sewer backups come from roots in a cracked private sewer lateral (City of Minneapolis). Stop running water and call a plumber.