Step 1: Turn off the water supply Turn off the toilet's water supply valve just below the tank. Flush the toilet to empty the tank. Hold down the lever to allow most of the water run out of the tank. Use a wet/dry vac to suction out the rest of the water if desired.
Turn the water supply handle cloclwise to turn off the water supply.
Step 3: Remove the old flush valve Remove the flush valve or flapper from the flush valve seat by lifting it out of the clips on the side or pulling it up and off of the overflow tube, depending on the type of valve.
Remove the flush valve by unclipping from the sides or lifting over the top of the tube.
Step 5: Attach the new valve and flapper Snap the tabs of the flush valve over the clips on the overflow tube, or slide it down over the top of the tube, seating the flapper level on the valve seat and ensuring a good seal.
Clip the new flapper valve onto the overflow tube and set the flapper level on the valve seat.
Step 6: Connect the new valve chain Connect the new valve chain to the trip arm by clipping it into the hole. Adjust the chain so that the flapper sits flat and has a good seal. Cut off extra links of chain that might interfere with toilet operation.
Step 7: Open the shut-off and test the new valve Turn on the water supply from underneath the toilet and let the tank fill. Once the water completely covers the flapper, water should stop filling the bowl. Test the new valve by flushing the toilet and watching the bowl fill. Once the flapper closes, all water to the bowl should stop as the tank refills.
The flapper will seal tight when covered with water and all water going into the bowl should stop.