My house has developed an annoying problem that I've searched the newsgroup for without finding anything similar...
My water pipes have started to give an annoying knocking noise but it does not fit the descriptions of hammering that I've read - ie. it isn't a knocking sound repeated in quick succession but a one-off knock that sometimes repeats after 18 seconds and sometimes after minutes. It doesn't happen all the time and is perhaps related to water usage in the house - sometimes it happens straight after using a tap and sometimes it happens later (perhaps even 30 minutes or more later). I've felt the pipe with the stopcock on it and can feel vibration when the knock occurs. I can also feel the vibration at any tap.
I've only noticed this in the past couple of weeks and the only things that have changed water-wise are moving to a metered supply just before xmas and opening the stopcock fully (previously it was almost closed and had been for years in an attempt to stop a leak - a plumber re-sealed it and since just before xmas it's been fully open).
Turning the stopcock off completely stops the noise as does leaving a very small trickle of water or fast stream of drips coming from a tap (I tried this with upstairs and downstairs taps). Obviously neither of these are long term solutions so does anyone have any suggestion?
Duncan