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How Do Water Levels Work in a Washing Machine?

Christie Gross

A water level or pressure switch monitors the water level inside washing machines. The switch alerts the washer’s main controls when to close the water valve after the washtub is filled to a specific level needed to wash a particular size wash load. If a washer under- or over-fills the washtub, the problem is often attributed to a broken water level switch.

Water Level Switch

A front-loading washing machine’s water level won’t ever be higher than the bottom of the door unless the washer is broken.

The water level switch is attached to the interior of the outer washtub. It’s a long, hollow and often plastic tube that holds air. As water fills the washtub, it also goes into the tube, pushing air toward the tube’s top. As the tub’s water level rises to a certain point needed for washing, the air pressure in the tube trips a switch to alert the washer’s controls to stop filling.

Water Level Setting and Adjustment

Conventional top-loading washing machines are designed to fill to a water level that you set from the washer’s controls based on the laundry load size you’re washing. Once the water reaches the level you choose, the water level switch activates to stop filling. To increase or decrease the water level on this washer type, reset the washer’s main control for a larger load size to ensure water completely covers the laundry you’re washing or choose a smaller load size to conserve water. Many front-loading washing machines have an automatic load size sensor that determines the amount of water needed for washing based on the amount of laundry in the washtub. This cannot be reset from washer’s controls.

Load Sensor

Many front-loading washing machines have a load sensor that estimates the load size in the washtub at any given time and automatically fills the tub to a level needed for washing. Based on the load size, water will begin filling the washtub, and the pressure switch will trigger just as it would on a top-loading washer once the desired water level is reached. You have no additional buttons to hit on the control panel.


If a water level switch breaks, the washer won’t fill properly. Depending on the issue, the washer will either under- or over-fill with water. If your washer has filling problems, inspect the water level switch for damage. A cracked or loose tube can affect a washer’s ability to reach a certain water level. Swap out the faulty tube for a new one. If you see water in the tube when the washing machine is off, the tube should be replaced. Contact a washing machine repair specialist to service the washing machine if needed.