I am having a similar problem , I think, although I can't really isolate it to the toilet. See, I have water leak somewhere. I have found no leaking pipes underneath the house, nor any soggy spots in the yard where the water service line runs to the house. My meter indicates that although I am not running any water, some water is being used or leaked somewhere. but here's the thing, i'll watch the meter and it will show that water is going somewhere...but then it stops. It's not like a continuous leak with continuous flow, but a leak that starts and stops every once in a while. My wife says that she's heard the toilet running when it hasn't been flushed in a while, so that's why i think i may be the toilet. It's run up my water bill and I'm not sure of what to do. I turned off the valve to the toilet and checked the meter for signs of activity, but as i said before, since it does it only at uncertain times, i don't know if turning off the valve isolated the problem or it just wasn't running in the toilet at that time. Anybody got any ideas? Thanks.