Pulsing mains supply problem & knocking noise

[WesleyS]

Hi, since yesterday I have been aware of a faint knocking noise on my mains inlet. The noise occurs every few minutes and varies in loudness then it will stop for anything up to an hour or so and then it will start again. This happened all through the night when everything is off. When I run the cold tap the water pulses, this is more apparent when the toilet refills or if I run the mains fed shower (you can feel it through the shower head). I’m on direct supply with no meter and the problem doesn’t appear to be aggravated by me using any taps in the house, I also have a combi boiler so no water tank.
Any help would be great!

 

[tipintim]

Turn off all outlets. Put a screw driver to the cold water main and put the other end to your ear. ( not the pointy end tho )
Can you hear water running.
Could be under ground leak.

 

[WesleyS]

Thanks
for the quick reply!

I have the washing machine on at the moment but will try the screwdriver thing
later. I’m not a meter and the banging noise occurs regularly unless I run a
tap. I’m waiting for my neighbor to come home as I will be asking them; I’m
hoping it’s a mains issue!

 

[TGor]

Try turning of the isolating valve to the WC cistern temporalily .. it may be the ballvalve bouncing if the noise stops replace the ballvalve!

 

[WesleyS]

Hi, I don’t appear to have an isolator for the WC, whilst under the sink the washing machine refilled and it is making a very definite whooshing pulsing sound, not a continuous noise but one like its flow rate is pulsing. As soon as it finished filling the knocking noise has returned, sort of 3 bangs like a hammer then a very faint couple of taps which are barely audible in a continuous cycle for about four minutes then it stops for a while and then starts again. I have also just checked the ballvalve and its motionless also if I hold the valve its not vibrating when the knocking noise occurs.