The Institution of Professional Engineers says New Zealand is running out of time to find ways of saving its fresh water.
It says areas such as Canterbury, Otago, Nelson-Marlborough, Waikato and Northland will be making maximum use of their supplies within four years.
The rising cost of electricity is forcing people to see power as a precious resource, and a similar incentive is needed when it comes to water, it says.
Director of public policy Tim Davin says most local councils charge households a fee that is based on the average water consumption in each area.
However, he says local authorities need to introduce meters so residents pay for the actual amount they use.
Mr Davin says that may encourage them to save fresh supplies by using recycled or rain water for uses such as garden irrigation.
