some unpleasant facts about coal to liquids, page-9

And on the subject of water consumption, you have to consider the price.
Urban water in australia costs about 1.50 a cubic meter. Farmers in the riverina have been paying about 1.00 for emergency supplies, which is more than 10 times what they usually pay.

A cubic meter of petrol is currently worth $1,700.00

So even if you were paying $5 a cubic meter for water and you needed 4 cubic meters of water to make a cubic meter of fuel, thats $20 of water for $1,700 of fuel. Its not a big deal.