Housing New Zealand has apologised for clearing 300 people out of state-owned homes that were found to have low levels of meth - some of whom had nowhere else to go.
A new Government report has found there's no evidence methamphetamine residue on household surfaces resulting from smoking the drug impacts health, contrary to former Government standards.
It means HNZ pointlessly emptied 240 houses and wasted a good chunk of $100m cleaning houses in which meth was smoked but not manufactured.
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HNZ chief executive Andrew McKenzie says the organisation is "absolutely" sorry for the situation, admitting to The AM Show that some tenants kicked out may have moved into their cars.
"That could well have been one of the consequences," he said.
"It's had some really regrettable consequences. Some of them we rehoused and some of them will have gone into other forms of accommodation.
"And in fact as an organisation we've moved to change our approach. So since the end of 2017 we longer ask people to leave and then don't rehouse them.
"We apologise to those people whose lives we've disrupted. It's not good enough."
But Mr McKenzie says HNZ had no choice but to work with the safety guidelines set by Standards NZ.
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"When the issue of methamphetamine contamination and potential health effects of it came up, the organisation went out and sought advice - this was over five years ago - as to what would be a safe level of contamination."
He says it's "pretty frustrating" to now realise HNZ was following incorrect advice.
"The Ministry of Health had guidelines which were the only things available for HNZ to use at that time. There was then a standards process that we went through where again, the scientists, the experts, said 'This is what we think is a safe level'."
Those people blacklisted by HNZ as a result of the meth testing have since had their names cleared, Mr McKenzie says.
Green Party co-leader Marama Davidson has since commended HNZ for "fronting" the issue, but says that doesn't go far enough.
"At the very least, HNZ should repay costs around testing," she says.
"Hundreds of HNZ and other tenants were put on the streets as a result of this bogus testing regime, then charged for the testing.
"All this was so National could appear tough on crime."
Standards NZ says it "stands by the process" which saw the vastly too conservative meth limits set.
"We are not experts in the science," spokesperson Carmen Mak told Mark Sainsbury on RadioLIVE.
"That's why the committee has access to that ESR (Institute of Environmental Science and Research) report commissioned by the Ministry of Health."
The 240 emptied state houses will now be refilled. Jacinda Ardern has confirmed private landlords who paid thousands to have their houses cleaned will not be compensated, as there was "never any mandatory requirement" for them to comply.