Residential water use in California is ridiculously high, even ignoring agriculture. Compare Sacramento's water usage per capita of 210 gallons per day[1]. In comparison, Melbourne's usage is 160 litres per day[2]. Even if you increase the number in that second link by 60% to add all the industrial use in Melbourne, it's still Sacramento at 800ish litres (~210 gallons) to Melbourne at 250ish litres. Humans are the same size in the two places, wear similar amounts of clothes, eat the same number of meals, and produce similar amounts of exceta.
It's just plain puzzling as to how Californians can use so much more residential water per person per day (a lot of it is probably the passion for really green lawns). If the complaint is that residential use is "only 20%" of total water usage, then reducing to Melbourne levels would mean you would save ~15% of that 20% - and a ~15% total reduction in water use by all sources is definitely worth doing.
Edit: This article has some more data points for residential use in different cities in California, ranging from a low of 46 gallons per day, up to 580 gallons per day(!!). 46 gpd is around the 160 litres for Melbourne above. 210gpd for Sacramento seems to be mid-range.
California's big cities tend to come in closer to Melbourne, or, in some cases, lower. The water districts cited at the top of that L.A. Times article cover huge areas, not, in most cases, individual cities, and some of those numbers likely do include agricultural use (not to mention golf courses and other questionable uses), despite the way they are presented.
Which makes even less sense - why would four times the population density use three times as much water per person?
It's weird that you're using both higher and lower population density ('more agriculture') as arguments for legitimately using more water. Also, I'm not sure if you know that Melbourne also has plenty of agriculture within it's city limits, lots of market gardens, and some farms out east. As for golf courses, Melbourne is somewhat known for it's "sand belt", an area full of golf courses because land is crap for anything else[1].
But no matter how much hand-waving you do, there's still only a couple of areas in California use as little water as Melbourne does, none use less, and plenty of it uses much, much more. Compton uses nearly 50% more water than the Melbourne average - where are it's agricultural industry and golf courses? Beverly Hills uses more than four times as much as Compton, and it has no agriculture or golf courses either (though it is next to one)
The point is that Melbourne is a perfectly workable city, and it gets by on a fraction of the per-capita residential use water that Californians do. Californian residents consume a phenomenal amount of water.
It's just plain puzzling as to how Californians can use so much more residential water per person per day (a lot of it is probably the passion for really green lawns). If the complaint is that residential use is "only 20%" of total water usage, then reducing to Melbourne levels would mean you would save ~15% of that 20% - and a ~15% total reduction in water use by all sources is definitely worth doing.
[1]http://greencitiescalifornia.org/best-practices/water/sacram... [2]http://www.melbournewater.com.au/waterdata/wateruse/Pages/de...
Edit: This article has some more data points for residential use in different cities in California, ranging from a low of 46 gallons per day, up to 580 gallons per day(!!). 46 gpd is around the 160 litres for Melbourne above. 210gpd for Sacramento seems to be mid-range.
http://www.latimes.com/local/california/la-me-1105-californi...