Housing New Zealand has ignored repeated warnings from senior government officials that the meth testing guidelines it was using to evict its tenants were only meant for houses where the drug had been manufactured.

Photo: Contaminated Site Solutions

The Ministry of Health has repeatedly told Housing New Zealand that its methamphetamine guidelines were to be applied only for the clean up of former meth labs, and were not intended to monitor homes where the drug has been smoked.

Yet hundreds of tenants have been evicted from their state homes, after Housing New Zealand detected tiny traces of methamphetamine in them, and are often made to pay tens of thousands of dollars in clean up fees.

The ministry has just published new guidelines saying meth can be found at three to four times higher than the level being used as a reason to evict tenants.

Director of protection, regulation and assurance, Dr Stewart Jessamine, said the ministry had repeatedly made clear it had concerns about the way Housing New Zealand was using the ministry's guidelines.

"The guidelines are very clear - that they are only for use in houses where methamphetamine has been manufactured. We have pointed out (to Housing New Zealand) and communicated that these guidelines are clearly for use in houses where meth has been manufactured," Dr Jessamine said.

HNZ caused huge harm - Drug Foundation

Drug Foundation executive director Ross Bell said Housing New Zealand had caused a huge amount of harm by knowingly misusing the guidelines.

"Housing New Zealand have evicted people out of HNZ homes, out of social housing, they have blacklisted these tenants for 12 months and they knew these guidelines were wrong," Mr Bell said.

"What do they do with the tenants that they've evicted, what do they do with the tenants who have been blacklisted, what do they do with the tenants who have been given $20,000 -$40,000 clean up bills?

"What are Housing New Zealand now going to do?"

Mr Bell said children had even been removed from their parents on the basis of the misused tests.

Green MP Marama Davidson said Housing New Zealand's conduct was deplorable.

"I am really struggling to know what to make of a government agency that seems as if it is actively looking to put more people into a desperate situation," she said.

The the Ministry of Health's published new guidelines say meth can be found at levels three to four times higher than the level at which Housing New Zealand is evicting its tenants before there is any possible risk to even a toddler's health.

Mr Bell said they were more appropriate, but he added the Ministry of Health had said nothing publicly while its former guidelines were being misused - not just by Housing New Zealand but in the private sector too.

He said the ministry had allowed a "cowboy" meth testing industry, and hysteria around meth contamination to flourish.

A senior lecturer in environmental chemistry at Massey University, Nick Kim, said the latest guidelines looked very sensible.

Housing NZ welcomes guidelines

A spokesperson for Housing New Zealand said the agency welcomed the Health Ministry's guidelines.

"We are currently considering its potential impact, however believe it will enable us to get homes back into the letting pool faster, as well as save costs around testing and decontamination," it said in a statement.

It said the guidelines provided clarity about the distinction between using meth and cooking meth (P lab).

The agency insisted it had actively advocated for a review of the Health Ministry guidelines.

Until a new standard was published in 2017, Housing New Zealand said it had been and would be guided by the Ministry of Health guidelines of 0.5g (0.5 µg/100 square centimetres) as the only current national 'standard'.

Standards New Zealand is expected to formally announce new standards for meth testing early next year.