It sounds like the beginning of a phone prank, but a running toilet is often an easy repair. The probable culprit: a faulty flapper. Here are the step by steps to get your toilet working smoothly again.

By Real Simple
Updated January 10, 2017
Fix a running toilet
Credit: Brown Bird Design

What You’ll Need

  • Most likely, a new flapper (the rubber stopper inside the tank)

What to Do

  1. Open the tank, reach in (don’t worry—the water in there is clean), and push down on the flapper with your hands. If this stops the running, it means the flapper has lost its seal.
  2. Shut the water-supply valve under the toilet. Flush the toilet to drain the remaining water.
  3. Remove the old flapper (and take it to the hardware store, to ensure that you get the right size). Follow the installation instructions on the new flapper, adjusting the chain that connects flapper and flusher so that the flapper lies flat, without too much slack in the chain.

Note: If, during step 1, the running doesn’t stop, the problem may be that the water level is too high and is draining down the overflow pipe (the plastic tube in the tank). The water level should be ½ to 1 inch below the tube’s top; if it’s any higher, adjust the float (the plastic piece that looks like a ball or a cup). For a ball float, bend the arm down; for a cup float, squeeze the clip to slide it down. If the running still doesn’t stop, it’s time to call in a pro.