The answer to 'shut-off valve overflowing' is that a shut-off valve that is overflowing or leaking is likely due to a problem with the valve itself or the plumbing system. Common causes include a worn or damaged valve, debris or mineral buildup, or a problem with the pipes or connections leading to the valve.
Symptoms of an overflowing shut-off valve include water leaking or dripping from the valve, the valve handle being difficult to turn, or water pooling around the valve. If the valve is overflowing, it's important to shut off the main water supply to the home as soon as possible to prevent further water damage.