Today the Independent Competition and Regulatory Commission has run the numbers on secondary water systems (rainwater tanks, wetlands etc) and come to the same conclusion reached over a century ago, that they don’t make any sense if your primary water system is functional.
Because of this level of security, there is little immediate value to the ACT community in investing in additional public secondary water initiatives. When ACT dams are full, as at present, the value of an extra kilolitre of primary water saved by using secondary water is the cost of treating the primary water and reticulating it to end-users, an estimated cost saving of $0.30/kL. This is much lower than the cost of providing water from any significant public secondary water option canvassed in the inquiry. Moreover, the value of secondary water in postponing the next primary water augmentation is also low as this investment is far distant.
Consequently, the Commission recommends that further public secondary water investments not be undertaken now.