What type of valve is commonly used for shutting off water supply in plumbing systems?

The ball valve is widely used in plumbing systems for shutting off water supply due to its design and functionality. This type of valve features a spherical disc, or ball, that has a hole in the middle, which allows or restricts the flow of water when rotated. Opening the valve aligns the hole with the pipe, enabling smooth flow, while closing it turns the ball so the hole is perpendicular to the flow, effectively halting water passage.

Ball valves are favored because they provide a reliable seal and can be operated quickly, allowing for immediate control over water supply. They are particularly effective for on/off services and have a long lifespan, making them a practical choice for both residential and commercial applications.

In contrast, the check valve is designed to prevent backflow, the gate valve is traditionally used for isolation but requires significant turns to open or close fully and may not provide as tight a seal over time, and the pressure relief valve is specifically engineered to manage pressure, not primarily for shutting off the supply. Each of these alternatives serves distinct purposes and functions within plumbing systems, but for the specific task of shutting off water supply, the ball valve is the most efficient and effective choice.