1. Determine the location of water shut-off valve The main water shut-off valve is usually in the basement or on an outside wall in a utility area of the house. It's noticed that this valve can be seen as the most important valse which allows water flowing through the pipe when it is opened. If homeowner find any serious leaking point or broken pipe, turning off this valve is the first step you need to do before calling a professional plumber. 2. Know how to use Plumber's tape correctly Plumber’s tape (also called Teflon tape) is used to seal pipe threads to prevent leaks around joints and fittings. You should typically wrap plumber’s tape three times around the pipe threads before sealing.