The Environment Court "erred erroneously" when making the decision to dismiss appeals against the expansion of the Otakiri bottling plant, says counsel for Ngati Awa.

More than 100 Ngati Awa whanau gathered in Rotorua yesterday as their fight to prevent the expansion of the plant, which would see over a billion bottles produced annually, reached the High Court.

Ngati Awa did not stand alone and was joined by Ngai Te Rangi, Ngati Pikiao and Sustainable Otakiri.

Creswell New Zealand, a subsidiary of Chinese company Nongfu, seeks to expand the plant and export the water overseas.

It's expected the expanded plant will provide at least 60 jobs in the district.

The Environment Court dismissed the group's appeals against the grant of resource consents by Bay of Plenty Regional Council and Whakatane District Council last year, as it felt it did not have jurisdiction over the "end use" of the water, which it said would happen in other nations.

This includes the consumption of the water and environmental effects of plastic waste.

Instead it could only consider the actual taking of the water aquifer.

However, counsel for Te Runanga o Ngati Awa Horiana Irwin-Easthope says the Environment Court has "erred erroneously" when making that decision and did not consider the local effects of the water plant, including how it could prevent the iwi from exercising its right to kaitiakitanga.

Irwin-Easthope says if the water is exported and Ngati Awa could not exercise that right, the impact of that would be felt "squarely" in New Zealand.

She notes that not all the water would be exported internationally, and some would be sold within New Zealand, therefore the plastic waste is a local issue.

She says it was made clear to the court that Ngati Awa is already practising kaitiaki and is attempting to reduce the number of plastic bottles in its rohe by banning them from its various businesses, including its boats.

As it decided it could not consider the "end use" of the water take, Irwin-Easthope says the Environment Court "closed its mind" to the actual, real, local outcomes of the water take.

She says this is a "fundamental error" and the matter should be referred back to the Environment Court with further guidelines from the High Court.

Counsel for Ngati Pikiao Environmental Society Rob Enright says the Environment Court failed to consider rangatiratanga as a relevant consideration for the resource consent.

He says as the Environment Court did not refer anywhere in its decision to rangatiratanga as put to it by Ngati Pikiao that was a "fundamental failure" to consider a relevant matter.

Enright says Ngati Pikiao's Treaty of Waitangi rights were missing from the decision.

"Treaty principles are mandatory and must be considered."

Enright also recommends the matter be brought back before the Environment Court so it could consider the spiritual effects on iwi.

Counsel for Ngai Te Rangi Jason Pou says his client wants to support its cousins in this fight.

He criticises the Environment Court's decision to rely on testimony from regional council experts on the mauri or life force of water, rather than those put forward by Ngati Awa.

Pou says the Environment Court opted to go with evidence presented by the regional council expert that the mauri of water is sustained wherever it went, because it would eventually be returned to the earth through its natural water cycle, as it aligned Western science to form the basis of the view.

Experts from Ngati Awa say the mauri is diminished when water is removed from its rohe.

Pou says the court can not simply agree with one individual and claim it represents the views of an entire iwi.

He says in their kaitiaki role, different iwi might have different ideas on how to manage their taonga but that is for the iwi to decide, not someone else.

"Who has the right of kaitiakitanga and who has the right to speak on behalf of a people about their spiritual connection to the water?

"When they listened to these views, they formed funnel vision, this funnelled what questions they asked and funnelled how they viewed the matter before them."

Pou says the iwi are consistent that extraction took the mauri from the water and to mix it elsewhere is offensive.

For the iwi to set aside its culture, it will need very good justification, he says.

Submissions in the High Court hearing are set to run until Thursday.

However, early indications are that it may be finished by Wednesday.

Today, the court is expected to hear from counsel for the regional council and Creswell NZ in the morning followed by counsel for the Whakatane council and Sustainable Otakiri in the afternoon.