Which valve is commonly used to stop or start the flow of water?

The ball valve is designed specifically to control the flow of water by either fully opening or fully closing the flow path through a sphere-shaped disc. This design allows for quick on-off operation, making it very effective for starting or stopping water flow in pipes. When the valve handle is turned, the ball rotates to either permit or obstruct the flow, providing a reliable seal that minimizes leakage.

In contrast, while check valves can prevent backflow and throttle valves can adjust flow rates, they are not primarily intended for starting or stopping flow completely. Check valves are designed to allow flow in one direction only, preventing reverse flow, which does not allow for complete shut-off. Throttle valves regulate flow to varying degrees rather than stopping it entirely. Pressure relief valves serve a different purpose—protecting piping systems from excessive pressure rather than controlling flow directly. Thus, the unique design and function of the ball valve make it the most suitable choice for stopping or starting the flow of water.