The Maori owners of Poroti Springs are angry local authorities approved variations to a resource consent at the site without consulting them.
In August last year Northland Regional Council (NRC) and Whangarei District Council (WDC) gave Zodiac Holdings Ltd approval to expand the earthworks for a commercial water bottling plant across the road from the springs.
The variation to Zodiac's original 2001 resource consent would effectively double the plant's footprint from 1850sq m to 3650sq m and its height from 7m to 10m.
Millan Ruka, from the Whatitiri Maori Reserve Trust (WMRT), said it was "insulting and beyond decency" that the councils deemed the variation non-notifiable rather than worthy of a new consent process.
He said representatives from both councils met with trust members in March only after they insisted they be put in the picture.
"This put us in the 'have a chat' process as the consent was already approved and nothing we could do about it," Mr Ruka said. "To top it off, we heard only the day before the meeting that the building was approved mid-2014."
Local hapu have fought for many years to stop the granting of permits for water from the aquifer, including through the Environment Court. Mr Ruka said it should be automatic for them to be consulted or at least notified of any processes affecting the site.
But Northland District Council monitoring manager Colin Dall said the council ticked off WDC's application for a variation on a non-notifiable basis because both councils were satisfied the effects of the earthworks would be minimal. Despite it being non-notifiable, the council told seven hapu groups about the application, Mr Dall said.
The trustees, however, believe that as the existing proposal is 14 years old, changes should be subject to a new consent process and publicly notified.
Mr Ruka said the original proposal did not take into account discharging wastewater from a bigger building and 16 staff, which he said would increase the risk of pollution.
A WDC spokeswoman said the variation was for earthworks only and at this stage there was no application in the system for the construction. The building would require a separate consent.
It would be during that process the building's size and height, wastewater discharge and other aspects would be considered.
Despite holding water permits since 2001, Zodiac has not yet taken a drop from the aquifer. Its associate company, New Zealand Spring Water, is seeking partnership deals in China and pre-marketing Poroti Springs water there under the brand name Thunder Mountain.