We have four systems on our project that we could potentially submeter.  However, from reading the LEED V4 Reference Guide, and this short article - https://leeduser.buildinggreen.com/credit/NC-v4/WEc4, I get the impression that we can choose which two we want to submeter.  This seems way to simple.  Do we have to choose sources representing the largest water usage, or do we have the flexibility to choose.

One option we're considering, is irrigation could be handled by adding a deduct meter at the water line when it enters the building. Then to get the irrigation flow we would deduct the meter at the building from the utility meter. Does this second option meet the LEED requirements?