that Zone 3 used much more water than any of the others. Zone 3 is an underground drip irrigation zone, with two parts -- one for the South bed, which now has Linda's second raised garden bed, and the North bed which used to have lavender plants (they died).
The South bed has a cut-off value for that bed.
and turning it off did not significantly change the water usage.
I did not originally have a cut-off valve for the North bed.
So I added a cut-off valve for the North bed.
But then turning this off still did not change the water usage. So there must be a leak someplace between the Zone 3 valve and the two beds.
Finding that leak, in the main supply lines way under ground is beyond my skill set, so I called American Irrigation Repair. They came out and found the leak in short order .. how they knew where to dig to find it, I don't know.
The leak was right at a joint -- a coupling -- as the main supply line for the South bed came out from under the sidewalk. The pipe had cracked right next to the coupling. They said it was because the pipe on one side was slightly lower than the pipe on the other side.
Making an in-line repair has always been a mystery to me, and they did this funny out and back to both allow the difference in height and to get enough flexibility in the pipes to put them together.
And that seems to have been that. $166. Quick, efficient and done right.