It usually happens on a Sunday night. The hamper is empty, the last load is spinning, and suddenly, your washer beeps an error code: You open the door, and instead of damp, clean clothes, you are greeted by a standing pool of stagnant water.

Here is the trick 90% of DIYers get wrong:

You are dealing with soft sludge, not tree roots. A snake will poke a hole through the sludge, but it won't clear the walls. The water will drain for a week, then clog again.

You have a .

You need the (or any expanding bladder bag). This is a $10 rubber nozzle that attaches to your garden hose.

But before you call the plumber (and pay weekend rates), let’s take a deep breath. This is one of the most common, and surprisingly fixable, plumbing emergencies in the home. Here is everything you need to know about why this happens, how to fix it, and how to ensure it never ruins your evening again. When water doesn’t drain, most people’s first instinct is to blame the machine. They assume the pump is dead. In 80% of cases, that is wrong.