Frank wrote:

I have a 1.6 liter per flush Kohler toilet - about five years old. This is
my problem. After I flush, all goes well. The water tank fills up and stops
filling as it's supposed too. This about fifteen minutes later, however, the
water tank slightly overfills and thus begins to pour into the overfull
hole. This is very gradual. I put a new flapper on it and it is not leaking.
Seems like the float level is OK as well because it stops short of overflow
when toilet is initially flushed.

What is causing the slow overfilling of the water tank and how can I fix it?

Any assistance is greatly appreciated.

Frank
you might also want to check the float ball to make sure its still
floating.. on one of my old toilets the ball was full of water and heavy
as hell and would sink down and not turn the water off as it would not
float all the way to the top of the water....