Why is my toilet humming?

Question

After one of my toilets is flushed, and it fills the bowl back up, I sometimes get a loud thrumming/humming noise.

It is the flusher stacky thingy making the noise. I turned down the volume of water flow into the toilet and it stopped making it. When it is doing it, the water tube from the wall to the toilet is literally vibrating in my hand.

Is this the water supply vibrating at a frequency that my flushy-stacky-thingy is exposing as noise, or something else?

Per Tester101's comment, I should note it only makes the noise, when the tank is full, and not running water through the pipes.

Answer 1

I'm guessing the valve assembly inside the toilet is finding a resonance when it's just about to close. You can replace it, and it's not too difficult of a DIY job. They sell just the valves:

But if you're going to take it apart to replace the valve, I tend to buy the full kit and replace all the guts.

Note that when my toilets started to leak, it was because of high pressure in the water lines. So it wouldn't hurt to pickup a pressure gauge that screws onto a hose faucet to make sure you don't have a bigger issue. After I fixed one, another would start leaking next as the pressure got a little higher.

Answer 2

I live in an apartment block and had a similar problem but it wasn't limited to the toilet, but it happened mostly with the toilet. I called it water rattle. I think the plumber called it water hammering.

It ended up being something to do with a fault water pump/water unit that connected with the outside water supply that serviced the building.

If it is the same thing, for us it got progressively worse over time. Initially it sounded more like a little rattle that would occasionally happen. In the end the pipes would clunk anytime you would use almost anything that uses water in the building. It took 3 plumbers to identify it in the end.