plumbingtoilet
When I flush my toilet it makes a very loud rumbling noise that can be heard from other rooms, what could cause this?
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.
You have a blockage that is in the main pipe downstream of where toilet and the bathroom drain collect, so it is backing up both of them. Since the chemicals are not doing it, it looks like it has to be augered.
Best Answer
Turns out the loud noise was caused by water rushing from other fixtures. The house had galvanized steel pipe as the main feed line (off the meter) which had become restricted, so when the toilet could not pull enough water from the main line it sucked it from other lines.
Replacing the galvanized pipe fixed the issue (as well as increased the pressure to the entire house).