I'm trying to fix a leaking toilet, and I can't seem to find a guide for the problem I have. Most of them are for fixing a leaky flapper or fill valve.

When I flush the toilet, the tank fills normally until it is full. I've confirmed that the float ball and valves are ok. After the tank fills up, I noticed that the filler tube (red arrow in the diagram) is bubbling and it sounds like the tank is continually being filled. If I move the float ball arm up a little bit, the leaking stops. I tried adjusting the height of the ball and tightening it, but the filler tube keeps bubbling.

Is this a problem with the float ball or fill valve?

enter image description here

  • If the fill valve is "leaking", the water must be going somewhere, or else the tank would overflow. Where's it going? Either the flush valve is leaking, or there's a leak in the overflow tube, or it's leaking out of the tank elsewhere (and not going into the bowl).
    – Dave Tweed
    Apr 15, 2015 at 21:22
  • When it's doing this, is the water up to the level of the overflow tube, or lower? If it's lower than the overflow tube, then I would expect that the flush valve is leaking. If it's leaking out the overflow tube then either the arm needs to be adjusted or the filler valve is just bad. Apr 15, 2015 at 21:56
  • @DaveTweed There's no water leaking, just the filler tube spitting out air bubbles, which sounds like leaking.
    – J. Lin
    Apr 16, 2015 at 0:54
  • @EricPetroelje it is below the overflow tube.
    – J. Lin
    Apr 16, 2015 at 0:55
  • 1
    For a couple of dollars and a few minutes of your time, you could simply replace the whole valve assembly. Why are you mucking about trying to figure out what's wrong?
    – Tester101
    Apr 16, 2015 at 11:01

2 Answers 2


I've run into this same problem several times, and tried the same things you're trying - adjust the ball, bend the arm a bit to put more pressure on the valve, etc.

Ultimately though I've always ended up replacing the fill valve. The pressure from the float ball and arm isn't enough to close the valve completely, a seal is worn out, or something else is similarly out of whack.

ETA: In my experience, the fill valves that don't have a ball but instead have a sort of integrated float seem to be less prone to this problem (like the one pictured below)

Fill Valve


As noted above, the fill valve is running and the water is going somewhere. It's not going into the overflow and it's not on the floor, ergo it's going into the toilet. Replace that leaky flapper (remember to check the drain for deposits or debris, some reason you're not getting a good seal) and your problem should be solved. I had exactly the same thing and the flapper was the culprit.

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