Hissing sound in cold mains pipes

[stanwaw]

As per @terryplumb - make sure your external stopcock is off fully, try opening kitchen tap, if it continues to run, I suspect the boundary (external pavement) stopcock is letting by.

A little update on this: you were right, the external valve was not closing fully earlier. Thanks to all of you who pointed this out. I had to repeat the switching off/on a couple of times as a couple of plumbers have come round to do the tests and provide quotes. The third time round, without me applying any particular force on the pavement valve, it switched off completely (no usage recorded at all at the meter).

Thames Water next for inspection.

 

[stanwaw]

If you find the leak there is no need to replace the whole service just fix it...

Thanks @Razor900. All specialists so far quoted for full replacement rather than fixing. They won't fix what they think is older, lead-based pipework (although I have the feeling it is copper, house is 1970s built). How can I insist on a fix?

 

[Razor900]

It won't be copper. If its 70s it could well be black alkathene pipe.

You need to find it first though @Hugh Jaleak has already told you the best way