Turn off the water supply to the toilet
Flush the toilet to empty the tank and bowl
Remove the tank lid and check for leaks
Tighten loose tank bolts and supply line connections
Replace a worn flapper valve
Replace a faulty fill valve
Replace a damaged flush valve seal
Check and replace the tank-to-bowl gasket if needed
Inspect the wax ring at the base of the toilet
Tighten the closet bolts at the base
Remove and reset the toilet with a new wax ring if the base is leaking
Replace a cracked tank or bowl if damaged
Turn the water supply back on
Test for leaks after repairs