I'm trying to troubleshoot an issue with a dual-flush toilet, where every few days it starts making a noise like there is an internal leak.

I popped open the tank hood and found that it's continually draining. I brought over a plumber, but when he showed up everything was working fine.

Here's a video: https://photos.app.goo.gl/bri4xneT6kuVKrwv6

So I waited a few days and the noise came back! I brought the plumber again, and of course there's no noise anymore. I start flushing it over and over again to reproduce this issue, but no "luck".

What do I do?

  • 1
    With it draining, probably the flush valve/flapper does not completely seal every time. Might just be dirt and need a good cleaning where the flush valve seals, or need a replacement valve. Both are things you should be able to do yourself, but your plumber will like the money.
    – crip659
    Mar 7, 2023 at 16:05
  • 1
    I deleted an answer about cleaning calcium off the flapper because, it was pointed out, your valve does not have a flapper. But it does have a silicone or rubber flush seal that performs the same function as a flapper and can be cleaned or replaced just like a flapper. I won't create an answer because I have no experience but you can find youtube videos on repairing Gerberit flush valves and sourcing parts. A new seal is about $5. I bet a fingernail is all you need to remove chalk buildup from it.
    – jay613
    Mar 7, 2023 at 18:26
  • Did you show your video to the plumber? Since that's about the only way to show him the thing "in the act", that seems to be the best bet...
    – FreeMan
    Mar 7, 2023 at 19:22

1 Answer 1


Some of these fancy flush mechanisms are just poorly designed - if you can't find something to fix, it's often easiest (after however many times you can stand calling someone in for a recurrent intermittent problem that won't show up when you have a plumber to look at it) to jettison the whole thing in hopes of finding one better designed.

  • By whole "thing" do you mean the whole toilet? Is it possible for me to switch out just the flush mechanism for a dual-flush system? Mar 8, 2023 at 19:10
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    Depending on the toilet/system, you may be locked into only the one they make for it, and in that case, if it's poorly designed so the mechanism is flaky (and the maker does not respond to your query with "oh, we came up with a better design, we'll ship one right out to you, sorry for all the wasted water!") then yes, you toss the whole toilet. If it's closer to standard you may be able to find a different system to swap in.
    – Ecnerwal
    Mar 8, 2023 at 19:18

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