Each fixture usually has a characteristic means of connection. Normal plumbing practice is to install a valve on each water supply line before the fixture, and this is most commonly termed a stop or "service valve". The water supply to some fixtures is cold water only (such as water closets and urinals). Most fixtures also have a hot water supply. In some occasional cases, a sink may have both a potable (drinkable) and a non-potable water supply.
Lavatories and water closets normally connect to the water supply by means of a supply, which is a tube, usually of nominal 3/8 in (U.S.) or 10 or 12 mm diameter (Europeand Middle East), which connects the water supply to the fixture, sometimes through a flexible (braided) hose. For water closets, this tube usually ends in a flat neoprenewasher that tightens against the connection, while for lavatories, the supply usually ends in a conical neoprene washer. Kitchen sinks, tubs and showers usually have supply tubes built onto their valves which then are soldered or 'fast joint'ed directly onto the water supply pipes.