Leak in tank?
I have a Kohler toilet which flushes fine,tank fills and bowl fills.Water apparently is leaking from tank into bowl, I did add coloring to water to ck. this. Tank refills and later I can hear the water running as if tank is again filling, turns off again until the tank needs to be "topped off" again. I have cleaned the opening and changed the flapper x 2 but have not solved the problem. Do I need a plumber? Thanks