I have a problem in a flat im working in where there is quite a loud water hammer. It only happens when the kitchen tap(lever shut off) is closed firmly. The tap has been changed but was doing it with the old and new one (both lever taps) The noise seems to come from where the incoming main is which is at the other side of the flat and no noise is heard in the kitchen where the tap that is causing it is. I have recently changed the PRV as the old one was leaking and i thought this was the culprit as the gauge would flick between 2.5 to 3 bar when the tap was turned off suddenly. Now im going to fit an arrestor but wondering do i fit it where the cause seems to be i.e the kitchen where the tap connects to the pipes or do it fit it where the noise is heard next to the PRV incoming main?