Discuss Noisy main cold water pipe, my plumber hasn't heard this before. in the General DIY Plumbing Forum area at Plumbers Forums


Hi Folks,

Would like to cast the net far and wide to try and get some resolution to this problem. The mains water coming into the property via a 15mm copper pipe, I have a Worcester Bosch Heatslave 15/19 around 16 yrs old to which the mains goes into - just above the boiler our plumber fitted a pressure valve to limit the pressure going into the boiler as we kept blowing the flow meter in the boiler every couple of years and we restrict the pressure to 3.5 bar. (property of down the side of a valley so we have mains pressure plus gravity). The noise would happen ranging from around 40 seconds to a couple of minutes usually mornings or evenings so we were checking the appliances that were running and what was being used in the bathroom etc, for a pattern. However the last 3 times this has happened it's been early in the mornings between 05:00 and 06:30 when there's nothing on whatsoever and hot water and heating on the boiler were both off via the timer. The noise itself sounds like an artic lorry pulling up outside the house, I have a feeling it's the inlet pipe violantly resonating as the valve on the pipe has been slightly weeping following one of the longer episodes, the plumber has had to replace a valve before due to the gauge filling up with water. As always with this type of problem it isn't reproducible, we're tried loads of permutations to try and reproduce it. The audio recording attached was taken on my iPad, the only time I've managed to capture the noise - hope it strikes a chord with someone out there who has had to deal with something similar. On hearing it my plumber hasn't heard such a sound before.
Can you rule out the possibility that the source is a neighbouring property? (Water pipes can propagate noise over quite long distances.)

Does turning off your water your stopcock or the one by the meter stop it?

Can you take a look at your water meter next time it happens to see if there is unexplained flow when it happens.

Judging from the "phhht!" noise when it stops, I'd point the finger of suspicion at a float valve or pressure reduction valve. At a stretch, it might be a crack, probably in a metal joint, opening when the pressure is high or in response to ground movement.

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