I have a little issue in my townhouse. When I flush the toilet, upstairs or down, after the water goes down the pipes make a low humming noise. Almost sounds like a horn. What is that about? :confused: Any suggestions greatly appreciated.

When the sound starts check each toilet to see if it's louder at one. If it is shut the water off at the stop under the tank and open up the ballcock and reverse the washer. Now just crack the stop and flush out the supply. Reassemble and test. Better now? Cheers, Tom

Sorry for not being a bit clearer. The sound is either coming from the main stack or the vent pipe not the toilets. Any clue what might be causing it?