Interactive water conservation tool/viz

[daguar]

Given CA's drought emergency, it'd be neat to have an interactive tool/viz to show people what effect different choices have on water usage.

(This idea is driven by comments on a KQED Forum show about how -- due to CA's mandates on high-efficiency plumbing -- the most effective levers are in fact not some of the basic residential stuff [e.g., shorter showers] but much more things like outside watering.)