Irrigation water is not the same as the clear and clean water that comes out of your kitchen sink. This water has undergone filtration asd is chemically treated with fluoride added so that it is clean and safe enough for us to drink.

Irrigation water comes straight from the river systems, stored in dams and delivered to farms via channels, with no chemical treatments or additives. As this water is not designed to be consumed, it does not need to be crystal clear like our tap water.
In Australia, water is a free natural resource. When we pay our water bills we are not paying for the water itself; but rather we are paying for how the water is delivered to us. Therefore, untreated water, delivered to farms via channels is going to cost less than delivering crystal clear water to suburban houses.
In addition, the volume of rural water delivered by rural infrastructure usually means that there are significant economies of scale savings when compared to urban systems,
Below you will find links to useful information: