Parliament has passed local government legislation which opposition parties say will lead to the privatisation of water supplies.
The Local Government Amendment Bill is part of the Government's law reforms designed to improve financial management, transparency and accountability.
Local Government Minister Rodney Hide said it would allow a council to contract with private sector companies to deliver water supplies for 35 years.
At present contracts can't run for more than 15 years.
"Councils cannot sell existing water service assets to private companies unless it is incidental to and desirable for the proposal's success,'' he said.
Opposition parties said that proviso had been sneaked into the bill at the last minute, after a select committee had heard public submissions on it.
"One can only imagine the intense lobbying that must have gone on, in secret, by powerful vested interests, to get this bill passed,'' the Greens' Sue Kedgley said.
"It would be very much in the public interest to know whether the Business Roundtable and the private water corporations have made large financial contributions to ACT and the National Party.''
Ms Kedgley said that as soon as a private company took over water supplies it would focus on maximising profits for its shareholders.
She said experience around the world showed that was achieved in three ways _ sacking most of the staff, charging more for water and allowing infrastructure to run down.
Labour's Phil Twyford said councils could hand over water supplies to private companies ``in the dead of night without consulting anyone...this bill takes away the democratic rights of New Zealanders and it is being rushed through under urgency.''
Maori Party MP Rahui Katene said she had real concerns about the future of water supplies ``and we have real concerns about things being sneaked in as well``
"This is about privatisation of water which hasn't worked anywhere else in the world,'' she said.
"Why are we following that track?"
The bill passed its third reading on a vote of 64 to 56.
