The flapper may be leaking due to a few potential causes.
- The flapper may not have been installed correctly; check that it is properly aligned and seated in the valve opening.
- The chain connecting the handle of the flapper to the water tank lever arm could be too short or too long, preventing its full closure.
- It is possible that the rubber seal on the flapper has worn out or become damaged, resulting in an improper fit with the valve opening.
If these suggestions do not resolve your leak issue, you may need to replace your new flapper altogether.