The answer to 'my shut-off valve is leaking' is that a leaking shut-off valve is a common plumbing issue that can be caused by a few different factors. The most common causes are mineral buildup, worn washers or seals, or the valve itself becoming damaged over time. Symptoms may include water dripping from the valve or even a steady stream of water.
In many cases, a leaking shut-off valve can be fixed with some basic DIY plumbing work. This may involve replacing the washers or seals, or in some cases, replacing the entire valve. However, if the valve is severely corroded or damaged, it's best to call in a professional plumber to assess the issue and make the necessary repairs.