Thats the thing……… the gound's the same as it usually is. We are on pretty sandy stuff here though so it could just disappear – but it seems odd.
I've narrowed it down to an existing section of galvanised pipe that we didn't replace (as it was under a load of concrete) about 6 years ago when we had a new feed to the house from the meter fitted.
This has two taps in it separated by about 7 feet. If I turn tap 1 off and leave tap 2 on the meter starts running – but stops when I turn tap 2 off as well, so I imagine the leak is between the two taps.
outbuildings—————tap1——————tap2—————————-meter
Inbetween tap 2 and the meter is the feed to the house and inbetween tap 1 and tap 2 is the feed to the office.
This is with the rising mains into the house and office turned off.
I'm kind of glad the bill turned up when it did, a couple of months of that usage and I'd be bankrupt.