Here is some more info http://www.mercurynews.com/drought/ci_27729990/california-drought-state-passes-mandatory-new-water-conservation?source=infinite it is a ban “from watering lawns and landscaping with potable water within 48 hours after measurable rainfall.” Given the rarity of rainfall in the drought, I’m not sure how often this will be necessary.
(as an aside, California is next to the largest body of water in the world. I’ll be drinking fresh desalinated water from it by the end of the year: http://carlsbaddesal.com/ )