Kohler K-11492-0 Class 5 toilet

My husband just install this class 5 toilet. It does the job. My question is : About 15 minutes after the flush and the tank refills, I hear the water running again as to fill the tank. My husband has adjusted the screw for the water level adjustment.
Kathy

The valve that holds the water in the tank is leaking. The fill valve is just doing what it's supposed to, keeping the tank at the proper level. Shut the supply off at the wall, and let it sit for awhile, and my guess is the tank will empty. If so, you may have something out of alignment, warped, loose, or kinked so the seal won't or can't keep the water in the tank. A close visual inspection will probably locate it.