What type of valve is commonly used to control water flow in plumbing systems?

A ball valve is commonly used to control water flow in plumbing systems because it provides excellent flow control and durability. This type of valve operates using a spherical disc (the "ball") that has a hole through its center. When the valve is open, the hole aligns with the pipe, allowing water to flow freely. When the valve is closed, the ball rotates to block the flow.

Ball valves are favored for their ease of use, quick operation, and minimal water resistance when fully open, making them effective for both shutting off and regulating flow. They are designed for a variety of applications, including both residential and commercial plumbing.

Conversely, a gate valve, while useful for on/off applications where full flow is needed, is not as effective for throttling purposes because it can create flow turbulence. Check valves prevent backflow and are not used for controlling flow direction. Relief valves are designed to release pressure from a system and do not regulate water flow in a continuous manner.