City councils in the Wellington region are on notice that urgent action is needed to safeguard water supplies.
Wellington Regional Council provides bulk water to four cities, Hutt, Porirua, Upper Hutt and Wellington, but says population growth is outstripping its drought scenario predictions.
It says unless the public conserves water more aggressively, a new dam will eventually be needed.
WRC chair Fran Wilde says water metering could cost about half the price of the dam, but decisions must ultimately be made by each council - and quickly.
