A running toilet wastes up to 200 gallons of water per day and adds $70+ to your monthly water bill. The good news — it is almost always a simple fix you can do in under 30 minutes with no plumber needed.
Remove the tank lid and listen. If water is trickling into the bowl the flapper is bad. If water is running over the overflow tube the fill valve or float needs adjusting. If water is leaking at the base of the fill valve the fill valve needs replacing.
Locate the shut-off valve on the wall behind or beneath the toilet. Turn it clockwise until it stops. Flush the toilet to empty the tank. Soak up any remaining water with a sponge.
Unhook the old flapper from the pegs on the overflow tube and disconnect the chain from the flush handle arm. Snap the new flapper onto the same pegs and reconnect the chain leaving about half an inch of slack. Turn the water back on and test.
Take your old flapper to the hardware store to match it exactly. Not all flappers are universal and the wrong size will cause the same problem.
If your toilet has a ball float on an arm, bend the arm slightly downward to lower the water level. If it has a cylinder float, pinch the clip and slide it down the fill valve shaft. The water level should sit about one inch below the top of the overflow tube.
Turn off the water and flush. Disconnect the water supply line from the bottom of the tank. Unscrew the locknut holding the fill valve in place and remove it. Install the new fill valve according to the package instructions, reconnect the supply line, and turn the water back on.
Turn the water supply back on and let the tank fill completely. Listen for any running water after the tank is full. Flush several times and confirm the running stops within 30 seconds of each flush.
If your toilet is still running after replacing both the flapper and fill valve, or if you notice cracks in the porcelain tank, it may be time for a full toilet replacement. That is a bigger job best left to a licensed plumber.
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