Things You'll Need
Adjustable pliers (optional)
If a toilet runs intermittently without having been used for a several minutes, this may signal that the toilet flapper should be replaced soon. A toilet flapper is the valve that opens when the toilet is flushed. Once the toilet tank has been emptied, the flapper moves into position over and into the tank drain. If the flapper begins to harden or deteriorate, this will cause the tank to slowly drain into the toilet bowl.
Turn off the water supply to the toilet tank. The water supply valve is often below the toilet tank at the end of the tank water supply hose.
Open the toilet tank lid. Flush the toilet and hold the handle down to completely drain the toilet tank.
Unlatch the flapper chain from the clip on the back side of the flush lever. If the clip has rusted shut, use pliers to pry it open.
Reach into the toilet tank and pull up on the flapper arms. Remove the flapper arms from the mounting posts on the toilet tank overflow-prevention pipe. Remove the flapper from the toilet tank and dispose of it.
Place the replacement flapper over the toilet tank drain, right side up. Attach the flapper arms to the mounting posts on the toilet tank overflow prevention pipe.
Remove the clip from the replacement flapper chain. Press the flapper down into the tank drain until the flapper is properly seated. Hold the chain up to the hole in the back side of the flush lever until the chain is taut but the flapper is still seated. Count off three links above the link closest to the hole in the flush lever and attach the clip to this link.
Attach the clip to the hole in the back side of the flush lever. Turn on the water supply valve and allow the toilet tank to fill. Flush the toilet as you would normally when the tank has stopped filling.