Since its a common feature request... can you tell us if its on the roadmap and if so any kind of rough timeline? I'd purchase a flow sensor if I could see real per zone data. My largest concern is cost, last august my water bill was just over $650 for water, most of which went to irrigation. If I could identify which zones were costing me the most, I'd put in the effort into optimizing those zones. focusing on proper head placement and even water distribution, leaks, catch cup tests, etc... Without real usage data per zone, there's no way I'd go thru all the work of investigating all 16 zones. I was really hoping Rach.io would pay for itself in savings, that doesn't seem to be the case when you live in a desert with very little summer rainfall but I'm optimistic with better data that it still can!