There is an eerie bass sound coming from our flush toilet. It sounds like this.

Usually it starts when we sit on the toilet or push it, but sometimes it starts even when we are away. Each time it starts, it lasts for several seconds, then halts.

Other than this, the toilet works fine - there is no apparent water-dripping.

What should we do? Do we have to replace the entire toilet? The entire water tank? Or just some part of it?

  • 1
    How do you know your toilet makes sounds while you're not there? Is this a modern indoor-plumbing version of "if a tree falls in the forest and no one is around to hear it.." ?
    – gregmac
    Commented Dec 8, 2014 at 15:49
  • 1
    I hear it from the living room... Commented Dec 8, 2014 at 15:52
  • Ah. Sorry, I read "when we are away" as meaning "not at home".
    – gregmac
    Commented Dec 8, 2014 at 18:04

1 Answer 1


Sometimes this is a resonant refill valve -- pushing the toilet, or a minor leak through the flush valve, shifts the water level just enough to open the valve a hair, and then it bounces between open and closed a few times until the water level comes up enough to close it more reliably. Fiddling with the water level may help, but replacing the refill mechanism is likely to help more.

(And since this is telling you that the flap valve is leaking a bit, you might want to consider replacing that too while you're at it.)

  • I concur, worn washers/seals/parts in toilet fill valves commonly cause a resonating noise and the intermittent nature indicates a leaky flush valve causing a slow level change. As for it starting when sat upon, the level is moving around a bit; check to ensure the toilet mount bolts are snug (don't overtighten them though!) Commented Dec 9, 2014 at 2:37
  • We replaced the refill mechanism and the noise disappeared. Thanks! Commented Oct 2, 2015 at 6:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.