Noisy Water Mains

[GrahamT]

Hi

I've been at a job where the owner was complaining about noisy water pipes. On seeing an overflow overflowing, I checked the storage tanks and noticed that the F&E float valve needed changing - so I changed that.
Anyway, everything works fine all over the house except that there is still running water noise in the mains. There are no signs of leaks, no taps dripping, nothing overflowing (WC, F&E CWSC). When I turn off the main stopcock, the noise stops.

I can't see any reason why the mains is flowing - I'm tearing my hair out!

Any help greatly appreciated.

Cheers, Graham

 

[gigz]

Ive had this before, turned out to be the lead mains pipe tee'd off under floor for an outside toilet and someone took toilet out and bent over the end of the lead and just hammered it flat, tucked the pipe back under floorboards and eventually it started leaking. Might be totally different but worth a punt.

 

[GrahamT]

it stops when stopcock in kitchen is turned off. appears to be between there and bathroom / tanks etc. above ground.

 

[gigz]

Is there any mixer valves ? (taps, showers etc) Cold main could be pushing hot water back (overflow would start again though) You may have to isolate individually