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 remove any remaining water from the tank.
Carefully remove the tank lid and set it aside on a soft surface to avoid breakage.
Inspect the flapper at the bottom of the tank for warping, cracks, or mineral buildup.
Unclip the old flapper from the overflow tube and remove it from the tank.
Install a new flapper by attaching it to the overflow tube and connecting the chain to the flush lever.
Ensure the flapper chain has slight slack when the flapper is closed to allow proper sealing.
Inspect the fill valve for signs of wear, improper shutoff, or continuous water flow.
If needed, replace the fill valve by unscrewing it from the tank and installing a new one per instructions.
Reconnect the water supply line to the fill valve and tighten with an adjustable wrench.
Turn the water supply valve back on slowly and allow the tank to fill.
Watch the flapper and fill valve during the refill to ensure proper operation and no leaks.
Adjust the float on the fill valve to set the correct water level, usually about 1 inch below the overflow tube.
Flush the toilet and observe the flush cycle to confirm the flapper seals properly and the tank refills correctly.
Check around the base of the fill valve and supply line for any signs of leaks.
Make final adjustments to the chain length or float height if needed for optimal performance.
Replace the tank lid carefully once all components are functioning correctly.
Test the toilet several times to ensure the running issue is resolved.
Clean up tools and dispose of the old flapper or valve properly.
