You can hear water in the toilet runs and then stop, what needs to be replaced. Thanks.. mark

Hi Mark

Most likely the toilet FLAPPER needs replacement. To test this, take some food coloring and drop some into the toilet tank. If colored water shows up in the toilet BOWL within a 1/2 hour or so then you have confirmed that the flapper is the issue. Bring the old flapper with you to a local plumbing supply store for the best possible match. You should also know the brand name of the toilet, OK?

Finally, sometimes replacing the flapper isn't enough as the FLUSH VALVE mechanism (the part the flapper sits on) is the part that is defective. In this case, flapper replacement won't work and you will need to replace the entire flush valve to stop the leaking!

Mark