The water fill on my toilet runs every 20-40 minutes. I have replaced the flapper several times with different brand flappers to no avail. I had a professional plumber in who recommended replacing the whole toilet. On his recommendation, we replaced the entire system. Including the reservoir tank, the bowl, and all associated hardware. The problem still exists. After replacing the whole system, we have replaced the flapper twice and even contacted the manufacturer for suggestions. They said that we should make sure to use their brand flapper. They sent one for free. The problem is still not fixed... any ideas?

 

This is a very odd problem that is hard to figure because it has happened with two different toilets. I would not assume anything so here is how i would approach it.

Have you ever proven the bowel is leaking water. Or is it just running into the overflow every 20 to 40 minutes?

If you are not sure start there. Turn the water off to it on some day when it is convienent. Over a day the tank water should drop. If it does and the surrounding area is dry then the flapper is leaking.

If the tank is still full then for some reason the valve is letting water in.

If the flapper is leaking the Plumber should be able to fix it as you paid him for his advice and followed it.

If it is the valve and you have an arm and ball for the float to control the water bend that arm down so it puts a greater amount of pressure on the valve. Consider changing the valve out to a fluid Master if the tank is holding the water.