I heard a rhythmic constant tapping a few days ago and thought it was probably our upstairs neighbour doing a bit of DIY. During the course of the day it continued and struck me that it might not be him.
I started exploring round our flat and found that it was loudest in our hallway cupboard where the meter is and where the supply comes into the flat. It's almost equally as loud on the other side of the wall where our electric shower is situated.
Shutting off the main inlet (before the meter) stopped the tapping, shutting off the supply to the shower (just after the meter on a branch pipe) did not.
Running either of the cold taps in the bathroom (even at a slowish trickle) stops the tapping noise, although I have noticed the water "pulses" as it's coming out of the taps.
The funny thing is, sometimes it doesn't do it. It doesn't [i]seem[/i] to be related to any appliances or the toilet. We have a compact push-button flush and the water in the cistern was calm whilst the tapping noise was present.
Any help greatly appreciated as it's starting to drive me insane! :)