I have a Kohler 1.6 gallon toilet, I just replaced the flapper - but every 20 minutes or so I hear a sort of rushing sound. There are no obvious leaks and I see no air bubbles inside the tank when this sound occurs. It is a 2-peice toilet and a few months ago I had a plumber change the seal on the bottom of the tank at which time a new flush was also installed. I have since replaced the rather flimsy flapper that came with the new flush, I have also used a tank cleaner. But the rushing sound still occurs - and the water level in the tank does not seem to go down.

Does anyone know what might be causing this sound? I am trying to avoid the costs of a plumber for what might be a simple solution.

  • take the lid off the tank, then sit down and watch the inside of the tank until the event occurs – jsotola Mar 10 '18 at 6:13
  • Watch both the tank level - mark it with some water proof tape or marking , mark the bowl level (use a grease pencil if need be) sit , wait and watch one or the other is going to move. – Ken Mar 10 '18 at 10:35
  • Modern flush valves are designed to signal a slow leak from the tank into the bowl by staying shut until the level of water in the tank goes a certain amount below the shut-off level and then coming on full force. Sounds like you have a slow leak probably around the flapper. You may have replaced what you thought was a flimsy flapper which sealed with a robust one which doesn't seal. If you still have the flimsy one, then maybe you should reinstall it. – Jim Stewart Mar 10 '18 at 11:22
  • I have removed the lid from the tank - that's how I know there were no bubbles. There is a stained water mark all around the top of the tank, when I heard the sound I watch very carefully but saw no movement in the water line. This was first occuring with the flimsy flapper that was on the flush that the plumber installed, so I purchased the so called "best" flapper - it is reddish & solid - the sound was still occuring after I installed it. I also think there is a very slow leak at the flapper - but the is even happening after installing the new one. – SH Queens Mar 10 '18 at 20:23

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