I can hear a leak dripping in the drain pipe below the toilet. I only hear the leak when I am displacing the water in the toilet boil. The more water displaced the greater the run off or drip. I've tested this by placing objects in the toilet bowl to displace the water. I've checked the tank and the flap doesn't leak and the water lever is 1/2 inch below runoff tube. Everything in the tank seems okay. Is this the design of the toilet to control the water level in the toilet bowl or do I have a bad toilet? I have a Kohler that's one year old and I noticed the leak shortly after installing it. There is no leak other than when filling the bowl prior to flush. Can you help?

If you hear the drip after you flush and the water siphons out then it doesn't sound serious. Does the bowl level drop while you hear the drip? If it doesn't then I suspect that what you hear is the very last of the water leaving the trap.
I only hear the leak when I am displacing the water in the toilet boil. You have raised the level in the trap so water will spill over into the closet bend. Perhaps one of the other experts can chime in with a different take on this. Regards, Tom

So you are saying it opnly leaks when you place objects in the toilet to displace water, if so that's how it is supposed to work. A 1" cubic object would displace 1" cubic volume of water. If the dripping noise totally stops after awhile then you have normal operation. Let me know if I misunderstood your situation.

You understand my situation, I kind of though this was how it was supposed to work, but never before heard a leak like this. Maybe I'm hearing it more because I have a long drop from toilet to first 90 degree turn. (about 4 feet). Thanks for your help.

You are also hearing it because under normal operation the flush noise would drown out this dripping. I'd stop putting things in the toilet and go was h my hands.