A leading group in the campaign against methamphetamine use says a planned rental housing warrant of fitness should test whether a house has been used as a P-lab.
The Auckland Regional Methamphetamine Working Group, which includes official agencies, drug experts and social services, says all homes should be tested for P residues when they are put up for rent or sale.
A member of the group, Meth Solutions director Miles Stratford, estimates that about 8000 homes are being used to manufacture methamphetamine at any time, and that thousands more properties have been used to make the drug in the past as drug users move from house to house.
North Shore Community and Social Services executive officer Yvonne Powley, who chairs the working group, said living in a meth-contaminated home had serious health consequences, especially for children.
"We think the number of houses used as P-labs is a lot higher than many people think," she said. "Landlords should make sure that properties are safe. It should be part of a warrant of fitness."
Housing Minister Nick Smith said Housing NZ began a trial warrant of fitness for state houses last month and would have initial results by July or August.
Meanwhile, the Auckland, Tauranga, Wellington, Christchurch and Dunedin City Councils are testing a draft 31-point checklist on 25 rental homes in each city.
Otago University Professor Philippa Howden-Chapman, who helped develop the checklist, said the cities hoped to introduce a revised mandatory test in one city to test its effectiveness.
She said councils were already responsible for enforcing housing regulations, which cover heating, amenities and numbers of people in each room but have not been changed since 1947.
"The only way we are going to get clarity is for councils to set standards. They can do local bylaws. Mayors in Christchurch and Dunedin have said they would do that," she said.
Phil Gregg of Tauranga-based Sustainability Options, who has tested 12 Tauranga rentals against the checklist, said all but one house failed, mainly because of poor insulation.
"There's usually something there but it's inadequate," he said. "It has just collapsed, which is typical of the older insulation - it collapses in anything from five to 15 years."
The last Massey University survey on illegal drug use found methamphetamine use "probably reached its peak in the early to mid-2000s".
Health Ministry surveys found 2.7 per cent of New Zealanders aged 16 to 64 had used the drug in the past year in 2003, 2.2 per cent in 2007-08 and 0.9 per cent, or about 25,000 people, in 2011-12 and 2012-13.
But Mr Stratford cited a finding in the Massey University survey that 32 per cent of frequent meth users in 2011, or about 8000 people, said they made the drug themselves.
"The thing with meth contamination is that it doesn't go away," he said. "It's not just what's happening today, it's what happened over the last 15 years."
However, Dr Smith said he did not support including a P test in warrants of fitness.
"Vendors or landlords may choose to get a P test done," he said. "But at this stage I do not think the scale of the problem warrants imposing a compulsory additional cost on all purchasers, sellers or landlords."
• The five-city pilot warrant-of-fitness checklist is on the Green Building Council website.
On the checklist, 31 items including:
• Is the area of mould less than the size of an A4 sheet of paper?
• Does the house have ceiling insulation to WoF standards?
• Does the house have underfloor insulation to WoF standards?
• Is the house weathertight with no evident leaks or moisture stains on the walls or ceiling?
Not on the list:
• Are there any P residues?