Banging noise from mains water

When I flush the toilet in the bathroom, run the tap or have a shower, when I turn the water off, I'm getting a really loud banging noise (loud enough to set the dog off thinking we're being robbed lol). Normally, you'd hear the cistern filling up after you've flushed, but I'm really not hearing any obvious noise of it filling up though it does eventually.

It's not been happening for long. Any ideas what it could be?

Hot water is through a combi boiler. Toilet, errr, it's just a toilet - back to the wall - you used to hear it clearly filling up after a flush, but now it could be about 5 minutes before I hear anything and I think that's the valve shutting off (you know how the sound changes once the cistern is filled?)

It's only started recently. We're currently getting prepared for external wall insulation, so gas pipes and all external pipework has been extended but that was only done in the last couple of weeks but I've been getting that noise since before that. The only water related pipework that has been touched is my external tap, but as I said, it's been going on longer than the work being done. It's not noisy when the water is running - it's after it's stopped running it starts banging

I'm in a 4-in-a-block maisonette type house and it almost sounds like it's above me, but it's only when my bathroom water is being used, plus my neighbour has been away for the past month.

Check your stop cock is fully open.

jj4091 said:

Check your stop cock is fully open.

Click to expand...

I know that the stop cock isn't fully open because if it is, the water pressure is immense - to the point that if you put the shower on (it's a mixer shower), the head flies off the holder and spins round the room like something possessed. I was told not to open it fully to keep the pressure at a reasonable level.

Try opening it fully then run a tap, if the banging noise stops then that is the problem & then you can get a decent plumber to rectify the problem with the shower.