Can anyone find any flaws in this argument? I was browsing through SA Water's website (
http://www.sawater.com.au) and was actually quite surprised what conclusions I reached when combining their facts together...
I have come to the conclusion that these water restrictions must be a political thing to win the "green" vote. The amount of water that they plan to save is so insignificant that it is a complete joke.

On average ~50% of Greater Adelaide's water is from reservoirs, ~50% is from the Murray

On average only 0.36% of water diverted from the Murray goes to Adelaide. The vast majority is used for irrigation upstream. Even if we didn't rely at all on reservoirs (i.e. it basically never rained here), this fraction would still be less than 1%.

45% of Adelaide water use is by Residential users

40% of residential use is for gardens and other outside use.

The water restrictions aim to reduce this 40% by some small fraction....
Hence these restrictions aim to cut back about 0.065% of the water used from the Murray to some smaller fraction (0.05% at the very least say, being very generous)
The same impact could be made by reducing the amount of water used by irrigation by some miniscule percentage (well under 1% - don't know exactly as exact figures aren't given on the website).
So surely resources should be spent on improving irrigation practices, rather than bothering little old Adelaide on how its residents should use their water