If I used 736 gallons a day I'd be paying... hmmm, six bucks a day for water. Actually that's not that bad, I pay more than that for coffee.
I'm interested in what you pay for water - The ceiling price on water "creation" (not including distribution) for countries near oceans with access to cheap energy (And Australia, for better or worse, has access to a LOT of cheap coal energy) - should be around $0.50/cubic meter according to this DBO (Design-Build-Operate) project in Singapore that Hyflux's SingSpring plant is going to deliver.
http://www.waterworld.com/articles/2013/09/singapore-s-secon...
A Cubic Meter = 1000 liters, so that should be 50 cents / 1000 or 0.05 cents/liter.
That would suggest that either Desalination has jumped ahead of what other sources in Australia cost, and Australia just needs to get desalination plants online, or, more likely, the bulk of the cost of water (in your case, 70-90%), comes from things like distribution, and not water generation.
IIRC, most of the drinking water comes from the local groundwater, and nearly all of the ag water comes from the Colorado like in the Imperial Valley
I've never understood why the California water boards don't just using pricing as a mechanism to moderate people's water use.