Though reticulated water in the ACT is among the most expensive in Australia, the commission says it is still less expensive than reusing water. In a foreword to the report, senior commissioner Malcolm Gray says that when primary water is plentiful, no secondary source delivers water as cheaply.

"Following the rains of the last two years, the very substantial investment in improving the primary water system and the sizable reduction in per capita consumption, primary water is plentiful at the moment and is likely to remain so for some time."

Because of this level of security, there was little immediate value to the ACT community in investing in additional public secondary water initiatives. However, managing Canberra's water security remained one of the most important challenges confronting the community.

Minister for Environment and Sustainable Development Simon Corbell said the report confirmed the government's decision to invest in water security projects.

"The government welcomes the ICRC’s finding today that the ACT will be water secure for at least the next 20 years, with only the possibility of a rare number of needs for water restrictions. This is a very pleasing outcome," Mr Corbell said.

Among the recommendations included in the 140-page report is stopping further roll out of storm water mitigation through the construction of wetlands in the ACT, as has been trialled in Canberra's inner north.

Mr Gray said there was no objection to using ponds to mitigate run off from storms, but until the north-side project had been evaluated, proposed stormwater capture at Molonglo and Tuggeranong should not go ahead.

The report says given the current level of water security, the commission found no solid basis for government subsidising private secondary water options. This includes the government subsidy of up to $1000 for water tanks at private residences.

Similarly, in relation to mandatory water efficiency requirements placed on estate developers, it was not evident the costs of government intervention were outweighed by the benefits. The commission recommends the ACT Government review these requirements within the context of an adaptive and integrated planning framework.

It also recommends the ACT Government introduce a residential greywater accreditation system, develop a clear approval pathway for multi-dwelling secondary water schemes, and develop an ACT third party water infrastructure access regime.

The report is critical of overall planning for Canberra's water needs. It says making good decisions in the face of evolving uncertainty and the wide range of potential supply and demand options requires an adaptive and integrated analytical framework, supported by clear lines of accountability and responsibility.

"The commission found no such framework in the ACT, but rather an unclear, disjointed and unresponsive approach to decision-making."