An estate owned by some of Auckland's wealthiest individuals controls more water from the Waikato River than the city of 1.6 million people itself.
And another has consent to take almost the same amount as the city of Hamilton.
A spokeswoman for Wairakei Pastoral Ltd, the largest consent holder, says the water caters for "current and future growth", and is used for a range of purposes such as irrigation on dozens of smaller farms - the majority in dairy.
While usage varied seasonally and with climate conditions, currently they were using less than a third of their allocation.
But Greenpeace, which obtained the information, says it is a "gross injustice" when Auckland's 40,000 businesses and 1.6 million residents - including nearly 30,000 farmers and people living on lifestyle blocks - continue under water restrictions sparked last year by one of the worst droughts on record.
Auckland gets about a third of its water from the Waikato River, and supplier Watercare plans to progressively increase this proportion to more than half over the next few decades.
But due to the river supply already being overallocated due to high demand, Watercare's application languishes well down the queue, mostly behind large dairy farms.
Wairakei Pastoral Ltd has a resource consent from Waikato Regional Council to take just under 153 million litres a day from the river, or 9.4 per cent of all water allocated, for its farming estate outside Taupō.
This is slightly more than the second-largest user, Watercare - which supplies Auckland's drinking water, with consent for just under 152MLD.
The company is owned by a selection of Auckland rich-listers including Ross Green, and Trevor Farmer and Mark Wyborn, who also control Viaduct Harbour Holdings which has vast estates around Newmarket and the city's downtown waterfront.
Meanwhile Wairarapa Moana Ki Pou, the fourth-largest user, has consent for just under 90MLD to use at its 10,695ha farm at Mangakino - slightly less than Hamilton City Council at 94MLD, and which is also currently under water restrictions.
Both companies have also separately applied to dramatically increase their takes - Wairarapa Moana Ki Pou another 90MLD and Wairakei Pastoral Ltd another 71MLD.
If granted, that would mean the two dairy operations could together use roughly the equivalent of Auckland's entire daily water usage at 400MLD.
Greenpeace director Russel Norman said the revelations demonstrated the problems of industrial farming, and the vast amount of resources required.
"It is a gross injustice that the 10 owners of Wairakei Estate have access to over 150MLD, when the 1.6 million residents of Auckland are trying to keep their water usage below 460MLD.
"And then to think of the tonnes of nitrogen pouring off the land [from dairy farming] and into the river, needing to be filtered before Aucklanders drink it, all just to make milk powder to make money."
In 2003 the company bought 25,000ha of forestry land, with aspirations to convert it into the largest dairy operation in the Southern Hemisphere.
In 2016 its main leaseholder, state-owned enterprise Pamu Farms of New Zealand (formerly Landcorp), which had been driving the conversions, decided to halt the process, citing environmental and financial pressures.
Pamu currently leases about 12,500ha, on which it farms 20,500 dairy cows, along with sheep and beef farming and a sheep milking operation.
Pamu spokesman Simon King said they only used "the water we need to ensure we farm in way that is sensitive to the environment and the welfare of our animals".
Norman said the way water was allocated needed to be addressed as the Government reformed the Resource Management Act.
"Rather than 'first-in, first-served', surely the first chunk should be going to the environment, second human consumption, and further down commercial interests."
Watercare, which has 117 applicants ahead of it in the queue for a resource consent hearing, made an application in 2013 to take an extra 200MLD from the Waikato.
It already has consent to take 150MLD and got a further 25MLD from the Hamilton allocation to help during the water crisis, and is working to secure 50 million more daily before next winter.
In September it was granted an additional 100 MLD, to take between May and September (inclusive), and at other times of the year when the river is above median flow.
A Watercare spokeswoman said it was not their place to comment on the other water users of the river.
"Auckland's water restrictions are in place due to the lack of rain we had in 2020 and are unrelated to our consented take from the river."
Auckland mayor Phil Goff, who had been highly critical of the RMA consent hold-up, declined to comment for this article.
Wairakei Estate is managed by Tramco, an Auckland-based property investment company with more than $1.8 billion of assets.
Tramco chief executive Angela Bull said the company was granted the consent in 2012 based on "anticipated needs" on behalf of a water-user group comprising 42 farms on Wairakei Estate, Southern Pastures, Happy Valley Milk and Huka Lodge.
She said the amount of water drawn from the river varies depending on seasonal conditions, but currently averages about 42MLD.
"It is common that usage is less than the allocation and water user groups allow for other entities, aside from the holder of the consent, to efficiently access water to support complementary uses such as farms and businesses and create opportunities for economic growth within their communities and regions under a single consent," Bull said.
Regarding the additional water consent application, Bull said this had not yet been processed and the company was currently reviewing their business needs and assessing whether the application was still required.
In 2019 the company drew criticism for attempting to keep its bid to change land-use from cropping to dairying, and hence increasing pollution levels, out of the public eye.
It was also criticised for allowing another company, Happy Valley Milk, to use some of its water allocation, by amending an existing consent to include a different catchment.
Waikato Regional Council declined to comment for this article, but chair Russ Rimmington has previously said the RMA legislation means they are required to process consents on a "first in, first served" basis.
The council had advocated "successive governments" for many years to change this, Rimmington said.
The total allocation was set in the 2012 Waikato Regional Plan, designed to ensure there was enough water to protect aquatic life and provide for recreation and electricity generation, while also meeting domestic, municipal, agricultural, cultural and industrial needs as far as possible.
As the river was already over-allocated during the drier months from October to April, they were unable to process new consent applications until other consents expired or were transferred.
The Herald has sought comment from Wairarapa Moana Ki Pou about its consent, and from Waikato River Authority and Waikato-Tainui, but received no response by deadline.
Auckland mayor Phil Goff declined to comment.
The victim was uninjured and ran for help to a nearby house to phone police.