I too live in lovely thirsty California.

I like to involve myself in bleeding edge stuff and just completed my landscaping several months ago. I installed the Rachio intelligent irrigation controller.

http://rachio.com

You enter your type of landscaping, soil, water emitters, zip code and it looks at local weather stations to automatically adjust your watering based upon what is going on and tells you how much you use and it will skip watering, lower or increased based on what is happening. It doesn't actually measure the water flow though. You can add ground moisture sensors but I don't think most end up doing this.

I am wondering whether EDIGs new water venture this will be a part of the Google's Nest Family. Lots of room for sensors in this arena, just wondering how it might help users save moola..