A group representing many iwi around the country say Māori must be given the right to freely use the water on their land.
The Iwi Leaders Group has held a hui in Wellington to discuss the government's planned freshwater management reforms, which are to go to Cabinet this year.
Te Tumu Paeroa chief executive Jamie Tuuta said in the 1970's, rural water schemes in Taranaki were funded by the government and local council rate payers.
He said in the past five years, the government has given the rights of two of those rural water schemes to the occupiers of Māori land, which includes lease land that Parininihi Ki Waitotara owns and other Maori trustee land.
"Those water rights have basically been handed for nothing to the occupier, the tenant, the leasee, and they [the rights] have now been separated from the particular parcel of land."
The Māori Trustee said a major constraint to land productivity is access to water.
Under current rules, some iwi have had farmland returned to them but do not necessarily get the rights to the water on that land.
Rongowhakaata iwi lead negotiator Willie Te Aho said the Crown needed to prioritise tribes concerns.
"We got back a farm outside Manutuke and we didn't get the water that goes with that farm. We just got the farm. The leasee owns the water that services that farm.
Mr Te Aho said they wanted to get on with development.
"When that lease ends, we have then got to look at how we secure water for our farm that we got through our settlement."
Iwi Advisers Group chair Donna Flavell said these case studies need to be demonstrated to the Crown.
"Even if we own the land, we can't access the water," she said.
The Iwi Leaders Group has been working with the government on its Freshwater Discussion Document which is due to be released to the public at the end of next month.
Ms Flavell said access was a key unresolved issue.
She said another key consideration for Māori was resourcing in terms of supporting whānau to participate in new arrangements.
"There are some really positive things that are coming out through some of these changes."
Ms Flavell said iwi needed to be engaging with regional bodies and making decisions on wider environmental interests in their areas.
The meeting was the first in a series of hui this month to consult iwi about the freshwater reforms, changes to resource management and Māori land laws.