That meant Housing NZ had needlessly evicted tenants over relatively harmless traces of meth, and in some cases required them to pay remediation costs.
Twyford confirmed today that in the two years to August 2017, 136 tenancies were terminated over meth contamination concerns and 363 individuals were suspended from applying for social housing.
"I want to apologise to people who were affected in this way," he said.
"I think it's appalling what happened."
The blame was laid squarely on the National-led Government, who Twyford said had "played along with the hysteria" over meth contamination and had "failed to provide any kind of leadership".
Former Social Housing Minister Paula Bennett was "gutless" for not fronting up and apologising, he said.
The inquiry would be exhaustive, looking at how many houses were tested, what the results were, and why each tenant was evicted.
Gluckman's report found that remediation in most cases was needed only in homes that had been former clan labs producing the drugs and where meth has been heavily used.
"I can't see the point of testing, full stop, unless the police or the forensics suspect it has been a place of synthesis," he said.
His report says that levels that exceed the current standard of 1.5mcg/100cm2 should not signal a health risk and exposure 10 times higher (15mcg/100cm2) would also be unlikely to have any adverse effects.
Because the risk is so low, testing is not warranted in most cases, the report said.