How to Clean a Meth Contaminated House
A structured, regulation-aware guide for New Zealand landlords — from discovery and independent testing through professional remediation, clearance verification, and preventing recurrence.
Important: This guide is for informational purposes only and does not constitute legal, insurance, or professional remediation advice. Landlords must always refer to the Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026, their insurance policy, and qualified independent professionals when managing contamination.
You Cannot Clean What You Have Not Measured
Cleaning a meth-contaminated house is not a cleaning task — it is a regulated, evidence-based process. Every decision, from what gets removed to when the property is safe to re-let, must be backed by independent laboratory results. The steps below follow that principle from start to finish.
Six Steps to a Cleared Property
Do Not Clean Until It Has Been Tested
The instinct to scrub, repaint, or rip up carpet the moment contamination is suspected is exactly what the 2026 Regulations are designed to prevent — cleaning before a formal assessment destroys the evidence you need and can spread residue deeper into the property. The critical nuance under the Act: property owners and landlords are permitted to clean low-level contamination (below 15 µg/100 cm²) themselves, but you cannot know whether you are above or below that line until the property has been independently tested. Test first — then the report tells you who is allowed to clean.
Screen First — Then Detailed-Test If Required
Under the 2026 Regulations, testing is a two-tier process. A landlord may carry out an initial screening assessment themselves, or engage someone to do it, to check whether meth is present and roughly at what level. If that screening indicates contamination at or above 15 µg/100 cm², the Act then requires a formal Detailed Assessment by a qualified professional using NIOSH Method 9111 surface-wipe sampling. That detailed report — room-by-room, individually analysed — is the factual foundation any remediation plan is built on.
Engage a Remediation Contractor — Separate from Your Tester
If your independent test confirms contamination at or above 15 µg/100 cm², the Act requires professional remediation — an owner cannot self-clean at this level. When engaging a contractor, the company that tests should never be the company that cleans. When the same business both identifies contamination and charges to remove it, a conflict of interest exists — the cleaner benefits from a 'failed' result. Engage a dedicated, IANZ-accredited decontamination contractor who works from your independent test report and will be independently verified afterwards.
The Remediation Itself — What Actually Happens
Professional meth decontamination is a staged, controlled process. The contractor establishes containment to prevent cross-contamination, then systematically cleans every affected surface using specialised chemical agents, HEPA-filtered vacuuming, and abrasive removal where residue has bonded. Contaminated porous materials are removed and disposed of as controlled waste. HVAC systems, behind appliances, and ceiling cavities are all addressed.
Post-Remediation Verification (Clearance Testing)
Once the contractor declares the property clean, you cannot simply re-let. The property must be independently re-tested — Post-Remediation Verification — to confirm methamphetamine levels have been reduced below the relevant threshold across all previously affected locations. This clearance test is the legal and insurance evidence that the property is safe to re-occupy.
Prevent Recurrence — Protect the Property Going Forward
Cleaning a contaminated house once does not protect it from happening again. Meth contamination is invisible, and without ongoing screening between tenancies a property owner has no way to detect recontamination early. Establish a documented testing regime — baseline screening at every change of tenancy — and consider MethShield for ongoing risk mitigation.
Screening Below 15 µg? You Can Clean It Yourself
Under the 2026 Act, if your screening assessment returns a result below 15 µg/100 cm², the property is not classified as contaminated — and the regulations permit you, the landlord or property owner, to clean it yourself. You are not required to engage a professional remediation contractor at this level. The steps below are for this self-cleaning pathway only; at or above 15 µg/100 cm² the mandatory professional process (Steps 03–05 above) applies.
After self-cleaning: re-screen to confirm levels have dropped further. While the Act does not mandate independent clearance testing below 15 µg, a follow-up screen gives you defensible, dated evidence that the property is safe to re-let — valuable for insurance and tenancy dispute purposes.
The Regulatory Framework
Before you clean, you need to know which rules apply. New Zealand has two parallel references — and they are not the same thing.
The 2026 Regulations (Rental Properties)
The Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026 apply exclusively to rental properties under the Residential Tenancies Act. Under the Act, contamination below 15 µg/100 cm² is not classified as contaminated — a property owner or landlord may clean it themselves. At or above 15 µg/100 cm² the property is contaminated and professional remediation is mandatory; above 30 µg/100 cm² it is uninhabitable until remediated and independently re-tested.
NZS 8510:2017 (The Reference Standard)
NZS 8510:2017 was not replaced by the 2026 Regulations. It remains the relevant New Zealand Standard for testing and remediation in non-rental situations — sale and purchase, owner-occupied homes, commercial property, insurance matters, and vehicles. The Standard's 1.5 µg/100 cm² clearance level is the defensible benchmark for post-remediation verification.
The independence rule: The company that identifies your contamination should never be the company paid to remove it. EnviroCheck tests and advises only — we do not remediate. Our clearance findings serve you, not a remediation invoice.