Meth testing | a 2020 house buyers guide

Meth testing for home buyers has come under the spotlight. Methamphetamine is an addictive stimulant that raises heart rate, elevates mood, increases energy, and promotes weight loss.

For a number of years people smoking meth inside was considered a major issue for future occupants. This has now been revealed to be without scientific evidence.

The history: In August 2010 the Ministry of Health drew up guidelines for clandestine ex-meth laboratories with an acceptable level of .05 µg/100 cm² of surface area in 2007.

Testing is generally over a 100 × 100 mm area where air movement takes place, ie, two-thirds of the way up window or door jambs, where smoke residue is likely to be deposited.

In June 2017 a new official Standard, Testing and decontamination of methamphetamine-contaminated properties, NZS 8510, was published with an acceptable limit three times higher: 1.5 µg/100 cm² of surface area.

This bump up of the limit allowed for the occasional smoking of meth without triggering the need for full decontamination. But it still meant that many houses needed extensive remediation. In some cases carpets, wall and ceiling linings, curtains, cabinetry were all replaced. This could cost tens of thousands of dollars.


With the 2017 change in government a full review of meth contamination in New Zealand houses was commissioned by new Housing Minister Phil Twyford.

The Chief Science Advisor, Peter Gluckman, found there was no scientific evidence of any health risk in houses where meth was smoked, and suggested a standard of 15 µg/100 cm². That is a big 45 times higher than the level of just a year previously.

Houses where meth is produced are still considered a health issue, as levels can be 300 µg/cm² or higher.

The result of all this is that houses that have some level of meth detected can usually be cleaned to satisfactory levels using Sugarsoap, a common commercial grade cleaner.

Also note that the use of meth has dropped over the last few years from a high of about 2.7% of the population in 2003, to 2.2% in 2009, to fewer than 1% nowadays.

And that it is now cheaper and easier to import meth, rather than find the raw ingredients and manufacture in New Zealand.

The outcome from the Gluckman Report is that if a house has been tenanted for a long period, it is probably still worth testing. But you do not need to completely renovate the premises if a low level of meth is found. If the levels come back as less than 15 µg it is enough to wash down the walls with Sugarsoap.

Washing the walls with Sugarsoap is probably good practice in any case, prior to moving in.

Older houses have more well-known actual health hazards, such as any paint from before 1980, that often has high levels of lead.

Recommendation: still test the house if it has been tenanted for extended periods of time, but don’t be concerned unless the methamphetamine levels are slightly over the new 15 µg limit. In 95% of cases a thorough washing of the walls, steam cleaning the carpets and curtains, will be adequate to reduce the contamination to acceptable levels.

The incidence of methamphetamine manufacture in houses is becoming less common, as the majority of meth is now imported.

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