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What Are the Causes of Washing Machine Backup?

The main reason a washing machine’s drain backs up is a clog. However, a couple of other problems can impact a washing machine’s ability to drain properly. If you open your washing machine and find standing water in the washtub, do some preliminary investigative work to see whether you can figure out why the washer is backing up.

Prepare to Troubleshoot

If the washing machine agitates but doesn’t drain, assume the motor is working properly.

Before you can determine what’s causing the washer to back up, you must drain the water from the washtub. Unplug your washer’s power cord from the electrical outlet. Refer to your washing machine’s manual for draining instructions. Usually there’s a small hose behind a flap in the back of the washer that allows you to drain water from within the washtub. Allow the water to drain into a large, waterproof container, such as a sink or 5-gallon pail.

Check for a Clogged Drain Outlet

A lost article of clothing or soap scum can both clog a washing machine drain and prevent the washer from completely dispelling all of its water at the end of a wash cycle. Review the washing machine’s manual for guidance on how to remove the washtub to locate the drain outlet. The drain outlet is the first place you want to check for a clog, since it’s the main entry point from the washtub to the drain line connected by the internal drain hose. Locating the drain outlet typically requires that you open the washing machine’s access panel and remove the internal drain hose. Once the hose is out, use a flashlight to peer into the outlet for clothing or debris. Use a pair of pliers or your hand to clear away anything that you find.

Clear the Drain Line

If you don’t see anything obstructing the washing machine’s drain outlet, the clog is farther down the drain line. Use a plumber’s snake to penetrate the drain outlet. Run the snake as far down the drain line as you can reach to clear the obstruction. Flush the drain line with warm water after you remove the snake to push out any fragments that may remain in the line. If you’re uncomfortable using a plumber’s snake, or if the snake isn’t long enough to locate the clog, contact a plumber to remove the blockage.

Bent External Drain Hose

Check to make sure that the washer’s external drain hose isn’t twisted. If the hose is kinked, the washer will be slow to drain or won’t drain at all, and possibly will back up because of the water pressure building up in the hose. Straighten the drain hose. If it’s damaged, replace it.

Disfunctional Pump

A washer’s pump pushes water from the washtub out the drain. If the pump breaks, water won’t exit the washtub efficiently and may cause water to back up into the washing machine. Contact a washing machine service technician to inspect the pump.

About the Author

Christie Gross has been writing since 1998. Her work writing public policy platforms for elected officials nationwide has been featured in national and local newspapers under various client pen names. Gross has a Bachelor of Arts in English and political science, as well as a Master of Public Administration from the University of Delaware.