Regional councils had been delegated the authority to manage water but they had never owned water, so had no power to give it away.
Mr Samuels said public statements by Environment Minister Nick Smith that nobody owned water had added to the confusion.
"The question I ask the government is: Who does own the water? In my view the Crown owns it on behalf of all New Zealanders. And if the government doesn't own it, they should legislate and make it very clear that it is vested in the Crown but owned by all New Zealanders.
"If you don't do that, what you get is misinformation and negotiations the public knows nothing about," he said.
By saying no one owned water, the government had given iwi leaders a chance to argue that it belonged to Maori. Mr Samuels also questioned how the government could delegate management of something it didn't own.
Iwi claims to fresh water arose after the part-privatisation of hydroelectric power stations in 2013. Iwi saw that as the government selling water rights to benefit a few shareholders, many of them offshore, when they had previously benefited all New Zealanders.
Government ministers met the powerful Iwi Leaders Forum at the Turner Centre in Kerikeri on February 5 this year in a bid to hammer out a deal.