The copper pipe that feeds the garden tap has started to leak - not sure if it's the cold weather or just old age. On investigation it appears to be the compression joint where the pipe exits from under the patio through a brick wall, to join an up-pipe to the tap itself. I can get access to about 10cm of the pipe (it's 15mm diameter), as I've drilled out the bricks adjacent to it, however the rest is just too deep under the patio to get to.
The pipe itself seems to be pitted, which might be why the compresion joint is leaking. I'd like to replace it with a soldered joint, but the seepage of water (as the house main doesn't turn the water off completely - there's still a slight trickle) would take all the heat out of the joint before the solder melted. I can't get access to any part of this pipe from the stop-c*ck to where it exits the patio wall - so freezing it is not possible.
Any thoughts, or techniques for fixing the leaky joint, preferably with something other than a compression fitting (because of the pitting) would be appreciated.