The most common cause of a leaking toilet is an old wax ring. The wax ring is a rubber ring that fits around the base of your toilet. It is used to apply a seal between the toilet and the flange.
The first step in fixing a leaking toilet is to shut off the water supply. If you’re at home, turn the main water valve off. If you’re at work, turn off the main water supply to the building. Next, you’ll need to remove the toilet top.
You want to make sure that the water is covering the rubber flapper. If it’s not, you may need to adjust the water level. Also, make sure that the flapper isn’t cracked or broken.