Watter Hammer

RE*AC*TOR

Usually after we flush the toilet, and sometime after running a tap we get this noise in the watter pipes. Recently its gotten worse to the point it almost sounds like someone is drilling in the walls. Running the kitchen tap stops the noise, but turning off the tap starts it again and i can even feel a vibration on the tap by placing my hand on it when its off.

I suspect that either A) the water pressure coming into the house is too high and / or there is air trapped in the pipes.

So what I want to know is what can I do about it (if anything), or do I need to get a plumber in?

Just to add a little more info: we have a three storey house, the problem seems to happen no matter which toilet is flushed, and I think the washing machine has caused it as well. It is audible on all floors, but I think the noise is worse on the top floor. Is it something to do with the cistern in the attic?

RE*AC*TOR

Ok, i popped my head into the attic, after flushing the toilet. There seems to be an ealier vibrating noise very soon after flushing the toilet that lasts maybe 5-10 seconds. Then several minutes later, I assume when the toilet / cistern etc has stopped filling there is a much more prolonged vibration (can last a few minutes).

The pipes going into the water tank are plastic, I had a feel when it was vibrating and I was able to identify the pipe that seems to be doing the vibrating.

This is the pipe -



I followed it down









Another pipe in the attic (some sort of vent pipe?), hardly a coincidence, but nonetheless a very worrying looking problem...

10-10-20

I have a feeling that loose piping will suffer from this issue more so than restrained or rigid or copper piping due to the fact that plastic piping will 'buck' when the reflected wave hits it. I have experienced this in our downstairs loo, but never on the rest of the system, and the loo is the only place where pipes run in the ceiling space without being firmly tacked down. I wonder if you were to insulate the pipes with normal pipe lagging and also tack them down or restrain them tightly, would it reduce the noise?

RE*AC*TOR

I lumbered my considerable mass up into the attic, which was no mean feat considering the aforementioned mass and the shortness of the step ladder.

Anyway I put the vent pipe in the last picture back into the hole. Its barely long enough to reach the hole, so I can see how it could slip out. Noise still persists, but the duration seems to have been significantly reduced (down to a couple of seconds then gone). It may just be a coincidence, will keep observing.

*edit* spoke too soon, noise back in all its glory