Valves provide several functions, including: Regulating flow and pressure within a piping system. Controlling the direction of flow within a piping system. Throttling flow rates within a piping system. Improving safety through relieving pressure or vacuum in a piping system.Washing machine valves control the water flow into the appliance, and reduce the risk and damage and leaks in emergencies. They can also be used on other common household appliances with water feeds.