FIRST: Carefully remove the toilet tank cover, it is breakable and sometimes impossible to match if you happen to break it, so be careful. Lay it on a towel or wrap it in newspapers.
SECOND: Put several drops of food coloring into the water tank above the toilet (not in the toilet bowl), be sure to put enough dye into the tank that you can see the color of the water change in the tank.
THIRD: Wait 15 minutes WITHOUT flushing the toilet. After 15 minutes, if the toilet bowl water is the same color as the tank water, you can assume you have a leak.
If there is a leaking toilet, more than likely you can fix it by replacing the flapper valve. If you are not 100% certain, simply give the Tampa plumbing professionals at Cass Plumbing a call. We will at your home fast. If it is a flapper valve we can usually fix that for you very quickly.
This simple plumbing test works great and will end up saving you money by stopping the constant water leaking into your toilet.