A toilet flush kit typically includes a flapper and chain assembly. These are sold in hardware and plumbing stores as replacements for flush kits that come with assembled tanks. The flapper connects to the flush handle by the flapper chain. Pressing down on the handle raises the flush rod and chain. This lifts open the flapper and allows the water inside the tank to escape, carrying away the sewage in the bowl. You can save money by replacing a toilet flush kit yourself, rather than calling a plumber.
Turn off the water supply for the toilet where you will be replacing the flush kit. The water supply valve can be found by following the tube or hose at the bottom of the tank to where it meets the supply valve at the wall. Rotate the knob on the end of the valve clockwise to turn off the water.
Remove the toilet lid. Press the handle to flush the toilet. Continue pressing down on the handle until all the water inside the tank empties. Wipe up any remaining water with the sponge and towel.
Disconnect the flapper chain from the flush handle. Examine the end of the flush handle rod where the flapper chain connects. Remove the chain by either unhooking the end of the chain, or use the needle-nose pliers to open the loop connecting the chain to the handle and pulling it off.
Remove the toilet flapper. There are a number of ways this can be done, depending on your flapper model. The easiest method is to unsnap the flapper from the hinge holding it in place at the bottom of the tank. Other flapper models may either slide off over the overflow tube or be inserted into the outlet on the bottom of the tank.
Replace the old flapper with a similar model. Follow the manufacturer's instructions for installation.
Connect the flapper chain to the flush handle rod.
Restore the water supply by turning the shut-off valve counterclockwise. Allow the tank time to fill. Flush the toilet and check for proper flush operation. Replace the tank lid.
A light coating of silicone grease around the underside rim of the flapper will help it keep a watertight seal.