The Chief Ombudsman Peter Boshier has released a report highly-critical of conditions at Northland's Ngawha Prison.
The Northland Regional Corrections Facility opened to much fanfare in 2005, with a stated aim of operating on tikanga Māori values, and turning around the lives of its majority of Māori prisoners.
But Peter Boshier said Ngawha Prison was persisting with policies that prevented it from achieving that potential.
Boshier has tabled his latest report in Parliament, following an unannounced inspection of the prison in February.
"Yet many of the processes and practices were more suited to a high-security setting and were impeding achievement of the prison's vision to develop a kaupapa Māori-based culture to support tāne to take their proper place in the community."
Population pressures and staff shortages had also limited progress, and the unintended consequences of some management practices had adversely affected the treatment of prisoners, the chief ombudsman said.
One example was an instruction that cell doors were locked while prisoners were exercising in the compound to reduce prisoner-on-prisoner assaults.
"My inspectors found that prisoners were resorting to urinating and, on occasion, defecating in the compound because of a lack of toilet facilities.
"This is pretty uncivilised in modern New Zealand," he told Checkpoint.
Inspectors were advised by staff of a restriction on access to drinking water in the yard - prisoners were not allowed to take water bottles or drinks containers there and instead to use the drinking fountain, which was integrated into the yard's lavatory.
The prison director was unaware of the situation and immediately revoked the restriction, Boshier said.
"Restricting prisoners' access to toilets and water is unacceptable and current mitigations were inadequate. I consider this to be degrading treatment and a breach of Article 16 of the Convention against Torture."
Prisoners had complained the most about cell conditions, specifically high temperatures and a lack of ventilation, he said.
"My inspectors found cell temperatures exceeding 28 degrees C and the kitchen was 38 degrees.
"In addition, both prisoners and staff reported long-standing shortages of both clothing and bedding."
And although 47 per cent of the prison's population was Māori, cultural provision was limited.
"Relationships between the prison and iwi were fragile, however, I am encouraged to learn of the willingness of all parties to overcome difficulties and provide a strong response to shared challenges," Boshier said.
"My inspectors observed generally positive interactions between staff and prisoners. Continuity of leadership, developing partnerships with iwi, and meeting performance standards consistently, will enable the prison's potential to be achieved."
The Department of Corrections has since accepted 28 of the Chief Ombudsman's 31 recommendations for improvements at Ngawha.
The report comes a day after Corrections launched Hōkai Rangi, a major new strategy focused on treating prisoners with respect and giving them more access to whānau.
The long-term strategy aims to drastically cut the number of Māori in prison from 52 percent down to 16 - to match the overall Māori population. It stated prison staff would be expected to treat prisoners with respect and uphold their mana.
In light of Hōkai Rangi, Boshier said the leadership and culture at prisons needed to be reviewed.
"It's really good to see the inspirational top leadership, but whether that's filtering down to individual prisons remains to be seen ... and I doubt [it].
"It's deplorable that the leadership has enabled this situation to occur."
He told Checkpoint it was time to make a change in the way prisons are run.
"This prison is not up to scratch. It's not having due regard to Māori culture and trying to do the best it can to ready prisoners for a proper culture and proper re-entry into the community; they're not being treated according to minimum standards."