[header] How to replace a water valve [title] Identify your valve type. [step] There are 3 types of valve connections, and your project's level of difficulty depends on how the valve connects to the water supply line. A threaded valve screws directly onto the water supply line and is easy to replace. 
In a compression connection, the valve screws into a hexagonal nut that fits around the supply line. The most difficult type to replace is a sweat valve, which is soldered onto the supply pipe.