The leader of the National Party says it's "incredibly frustrating" that they received incorrect advice on meth testing in houses, which ultimately put people out of their homes.
A Government report released last week found no evidence methamphetamine residue on household surfaces from smoking impacts health.
"We're not technical experts," Simon Bridges told The AM Show on Tuesday morning.
"We asked what we thought were the right questions - the hard questions - we were sceptical. We wanted a review... We got the wrong advice."
- State houses needlessly emptied where meth previously smoked - report
- National had no idea meth guidelines were wrong - Judith Collins
- Meth tester already knew 'contaminated' houses had little health impact
It means Housing New Zealand (HNZ) may have pointlessly emptied several hundred state houses and wasted a good chunk of $100m on cleaning houses in which meth was smoked but not manufactured.
As a result of the report, 240 state homes with low levels of meth will be released within weeks for people to live in.
The Drug Foundation's Ross Bell is calling meth testing the "biggest scam New Zealand has ever seen" - but Mr Bridges is denying that claim.
"Why would we do that when we wanted people in houses? You were there - it was the big issue of the election."
"We were in the position of having to put the health and safety of the people who might be going into those houses first."
HNZ will now use a new standard of 15 micrograms of meth detected per 100 square centimetres after cleaning, expecting to save $30m a year in remediation and testing. That's 10 times the current limit of 1.5 micrograms. It used to be 0.5 micrograms after cleaning.