The country's top scientists say New Zealand has been gripped by hysteria and are recommending people do not test their homes for meth - unless the Police specifically indicate it was a meth lab.
A new report by the Prime Minister's chief science adviser Sir Peter Gluckman found there's never been a documented case of someone getting sick from third-hand exposure to meth.
Sir Peter said there has been an inexplicable leap in logic in New Zealand in which clean-up standards for meth labs jumped to become a measure for passive exposure.
"There's absolutely no evidence in the medical literature anywhere in the world, of anybody being harmed by passive exposure to methamphetamine at any level," Sir Peter said.
"We can't find one case in the medical literature, we can't find one case by talking to experts where there is evidence of harm ... it makes no sense."
Dr Anne Bardsley did most of the work on the report and she had this advice for people considering getting their homes tested: "If people have no reason to think that it was [a meth lab] we would recommend them not testing - that has been driven by the industry."
Sir Peter said in most other countries where meth was used, homes were not routinely screened for traces of the drug.
He said the bulk of methamphetamine was imported and not made here, and "even the ones that are here are probably using sealed container methodologies now rather than the old solvent releasing methodologies so the risks are very low to the New Zealand population".
"I can't see the point of testing fullstop - unless the Police or the forensics suspect it has been a place of synthesis," Sir Peter said.
Housing Minister Phil Twyford said dodgy meth contamination rules have led to hundreds of millions of dollars being wasted and people being unnecessarily evicted from their homes.
Mr Twyford said it had led to needless clean-ups and evictions.
"A hundred million dollars in the case of Housing New Zealand, goodness knows how much in the private sector - so money's been wasted," Mr Twyford said.
"Hundreds and hundreds of homes have been left vacant in the middle of a housing crisis and many hundreds of tenants, individuals and families a significant number of whom will have been evicted on the basis of faulty information."
Hundreds of state houses previously thought to be contaminated will immediately be made available for tenants.
Mr Twyford said the enormous remediation costs that the Tenancy Tribunal has hit Housing New Zealand tenants with for tiny traces of meth in their homes was "not fair".
The Drug Foundation is right behind the policy turn-around but its executive director Ross Bell said the report was years too late.
"The report's blown us away, it's clearly a very scathing report condemning the whole approach that New Zealand's taken around methamphetamine contamination. But it's a report that was needed a few years ago," he said.
"It's a very sobre and thoughtful analysis and I think it puts to bed a lot of the fear and hysteria that's been generated."
He wants to know how people wrongly evicted from their houses because they were deemed methamphetamine contaminated can been compensated.
"The real harm has been the social harm where people have been essentially wrongly evicted from social housing including Housing New Zealand who have then been taken to the Tenancy Tribunal and had all those costs awarded against them and then being stood down from accessing social housing."
The government has ordered an investigation into Standards New Zealand which developed new meth testing guidelines last year, because they are at such odds with Sir Peter's report.
That guideline suggested 1.5 micrograms of meth per 100cm² as the appropriate new standard for the clean up of meth-contaminated properties.
Sir Peter said that should only apply to former meth labs or heavy use is suspected, and is recommending a new level of 15mcg per 100cm2 be adopted for other properties.
"There's still probably a 1000 to 10,000 safety factor involved with the 15mcg cut off that we are recommending."