Every 40 seconds my toilet "fills". I have opened the back and manually straightened the flapper,

[2naSalit]

11. I was just about to...

Go investigate why my toilet has started doing that.. Mine is less than four years old but we have incredibly hard water here. I go through a lot of vinegar cleaning mineral deposits from everything that touches water.

I'm suspicious about the mineral deposits and think that the plugging device may have enough crust on it to leak into the bowl. I'm on a high hill and the water level in the bowl seems to change with the weather.

I'm going to flush it, pour half a gallon of vinegar in the tank, let it sit for an hour or so then flush and see what happens.