A toilet’s shutoff valve operates only to stop the flow of water from entering the toilet if the toilet requires service. Within the toilet’s shutoff valve are a number of seals. Because a toilet’s shutoff valve is rarely turned off, the seals within the valve tend to dry out and eventually crack. Once the seals crack, the valve will leak. Although the valve cannot be repaired, it is relatively simple and inexpensive to replace.
Turn off the house’s main water supply valve with a wrench at the water meter.
Flush the toilet repeatedly until the toilet no longer fills with water.
Lift the cover off the back of the toilet’s tank and use a sponge to remove any remaining water inside the tank.
Disconnect the hose that connects the shutoff valve to the bottom of the toilet’s tank. Twist the in-line nut at the tip of the hose, where the hose attaches to the shutoff valve, counterclockwise with an adjustable wrench until the line detaches from the valve.
Grasp the base of the shutoff valve with an adjustable wrench, then twist the valve counterclockwise until the valve detaches from the water supply pipe.
Scrape any mineral deposits off the threaded tip of the water supply pipe with a wire brush.
Apply plumber’s paste to the threads of the water supply pipe with the brush included with the paste.
Hand-tighten the replacement shutoff valve onto the threaded tip of the water supply pipe, then tighten the valve onto the pipe with an adjustable wrench.
Turn the valve’s handle counterclockwise until the handle stops to turn the valve on.
Position the water supply line connected to the bottom of the toilet’s tank onto the threaded fitting at the top of the shutoff valve, then tighten the integral nut at the tip of the line onto the shutoff valve with an adjustable wrench.
Turn on the house’s main water supply valve with a wrench at the water meter and allow the toilet to fill with water before using it.