Assuming the well is consistent, I have the test that is required by the Province whenever a well is re-drilled that tells me the exact amounts of all sorts of things in the water.
Still researching a bit, and I've brewed with both conditioned and raw unfiltered, unconditioned water to see if there is a blatant difference, but haven't come to any conclusion yet.
Watched the first of a series of videos online, going to watch the rest soon.
Thing is, when the beer is already good>very good, it's tough to be too worried about efficiency, when really it's another buck in grain to balance off against efficiency issues.
JQ