On Sat, 17 Sep 2005 14:39:52 +0100, "N Cook"
wrote:


"Michael Gray" wrote in message
.. .
On Fri, 16 Sep 2005 11:37:48 +0100, "N Cook"
wrote:

By excavating pits and freezing the pipe I localised down to a 20 foot
run
and then a 10 foot run. I've now dug 2 more pits so about 3 foot
apart in that 10 foot. 3 gallons of water an hour is just disappearing
with no trace emerging along pipe or into holes.


While I wait for more water to freeze in the freezer to
localise a bit more, anyone any ideas for electronically/
audibly trying to localise the leak. A listening stick made from a steel
rod and a wooden drawer knob certainly works against anywhere
on the pipe (thats the problem ,anywhere ,
and much same level) but nothing through the soil

Have you considered using smoke to test for leaks?
http://www.hurcotech.com/

I did consider digging out an air pump , turning off the supply at the
pavement
and blowing air back into the piping to see if it would whistle where the
leak is.


Listening for potentially non-existent whistles, is about 90% less
reliable than looking for smoke.
Plumbers often put peppermint essence in smoke, so that if it can't be
seen, there is a very good chance it can be smelled.

Plumbers have been using this method for hundreds of years, and have
yet to change it, for the good reason that it works.
And it's cheap.

Why re-invent the wheel?
Your local plumbing supplier should have smoke bombs for this very
purpose.