Turn off the toilet's water supply valve located behind the toilet by turning it clockwise.
Flush the toilet to drain most of the water from the tank.
Use a sponge and bucket to soak up and remove any remaining water in the tank.
Inspect the rubber flapper at the bottom of the tank for signs of warping or deterioration.
Unclip the old flapper from the overflow tube and remove it if it appears damaged.
Install a new flapper by attaching it to the overflow tube and connecting the chain to the flush lever.
Check the fill valve to ensure it shuts off properly when the tank is full.
Adjust the fill valve float height so the water stops about 1 inch below the overflow tube.
If the fill valve is faulty, remove it by unscrewing the locknut underneath the tank.
Install a new fill valve according to the manufacturer’s instructions and secure it in place.
Reconnect the water supply line to the fill valve and hand-tighten with an adjustable wrench.
Turn the water supply back on slowly and allow the tank to fill.
Observe the tank as it fills to ensure the flapper seals properly and water stops at the correct level.
Flush the toilet a few times to confirm the flapper and fill valve are working correctly.
Adjust the chain length on the flapper if the flush handle feels too tight or too loose.
Check for any leaks around the base of the fill valve and tighten connections if necessary.
Ensure the float moves freely and does not get stuck against the tank wall.
Use Teflon tape on threaded connections if minor leaks persist.
Replace the tank lid once everything is functioning properly.
Clean up any spilled water and store tools and materials.
