A washing machine pump is a device used to extract the water from a washing machine. Following both the rinse and wash cycles, the washing machine pump is activated and pumps the water from the washer to the drain pipe and into the building's plumbing system. Often capable of pumping large quantities of liquid in a short time, the pump allows the washing machine to empty itself with no further assistance from the operator of the machine. If rendered inoperable, the pump unit is removable by an experienced repair person or a mechanically-inclined owner of the machine, which allows a replacement pump to be installed.
Early versions of the washing machine did not include a washing machine pump. The water was simply emptied from the washer via a hose mounted low on the side of the machine. The operator used the hose to drain the wash water into a bucket and then poured the contents of the bucket into a suitable drain. In some households, the water was simply allowed to pour into a drain located in the floor of the room housing the washing machine. To fill the machine, the user filled a bucket with clean water then poured it into the washing machine.
The washing machine pump aided in making the washing machine an in-home appliance instead of it being limited to a porch or basement area. The natural follow-up to the invention of the washing machine pump was internal water lines, which allowed attachment of the machine to the home's inside plumbing. The key to operating a washing machine inside of the home without having large water leaks from the drain system is to keep the drain hose mounted above the washer's water level. The washing machine pump can push the water up and out of the drain hose and allow it to drain into the home's plumbing system. The height of the drain hose prevents the water from prematurely siphoning out of the washer.
Screens protect most pumps from becoming plugged with lint and other debris stemming from the wash cycle. Occasionally, the washing machine pump will require cleaning to remove material from the pump body as well as the screen. When this occurs, it is commonly best left to a trained repairman in order to prevent leaking and poor performance. Technological advancements have resulted in washing machine pump designs that typically give proper performance for the life of the washing machine in most cases.