In the standard wall-mounted cooler, also commonly referred to as a water fountain or drinking fountain, a small tank in the machine holds chilled water so the user does not have to wait for chilled water. Water is delivered by turning or pressing a button on a spring-loaded valve located on the top of the unit, that turns off the water when released. Some devices also offer a large button on the front or side. Newer machines may not have a button at all; instead a sensor that detects when someone is near and activates the water. Water is delivered in a stream that arches up, allowing the user to drink directly from the top of the stream of water. These devices usually dispense water directly from the municipal water supply, without treatment or filtering.