A major report by the Waitangi Tribunal calls for a radical overhaul of water management and reform of the Resource Management Act.

The National Freshwater and Geothermal Resources report responds to a 2012 claim filed by the Maori Council.

The inquiry's been looking into whether laws on fresh water are consistent with the principles of the Treaty.

Maori Council executive director Matthew Tukaki says it's clear the Resource Management Act's not fit for purpose.

"We have a patchwork of implementation differences around the country when it comes to local government, which has led to the over-allocation, in some cases, of water."

He says unless we do something now some waterways won't recover.

"That's not something just of interest to Maori people but it's of significant interest to all New Zealanders, so that's why we believe change is needed."

The report also pushes for a working group between Maori and the Crown.