Nobody uses that much water to grow indoor weed. Plenty of grow guides around, if I remember correctly water every 3-5 days depending on if coconut fiber or soil, and pot size, flush daily towards the end of the flowering cycle.

Meanwhile, the average California household was estimated in 2011 to use more than 360 gallons of water per day. http://blogs.kqed.org/lowdown/2014/01/23/how-much-water-do-c...

Of course nothing was said about the wine industry, or how California uses 6 billion gallons of water annually to irrigate highway vegetation.