As a rough check, using the number properties in Victoria that pay water rates x the 55 cents per day would give an approximate way to verify.
For example "if" there are 3.3m to 4m water ratable properties, x the 45 to 55 cents would = around the $1.8m per day reported cost of the desal plant.
(Obviously the correct number of Victorian water ratable properties needs to be ascertained for the calculation to be accurate).