Meth contamination can be difficult to understand, especially when a test report shows a number such as 15 µg/100 cm² or 30 µg/100 cm².
What do these numbers actually mean? Does a result below 30 mean the property is acceptable? What happens when a result is above 15? And why are there two different meth contamination levels under New Zealand’s 2026 residential tenancy rules?
Understanding these levels is important for landlords, tenants, property managers, homeowners and anyone dealing with a property that may have been affected by methamphetamine.
Under the Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026, two important thresholds apply:
- 15 µg/100 cm² — the maximum acceptable level
- 30 µg/100 cm² — the maximum inhabitable level
These two numbers have different legal meanings and should not be treated as interchangeable.
For the latest requirements, see the official Tenancy Services guidance on meth contamination and the Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026.
What Are the New Zealand Meth Contamination Levels?
The Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026 came into force on 16 April 2026.
The regulations set the maximum acceptable level of methamphetamine residue at 15 µg/100 cm² for residential tenancy premises. They also set the maximum inhabitable level at 30 µg/100 cm².
This means a test result needs to be interpreted carefully. A result between 15 and 30 is different from a result above 30.
For landlords and property managers, understanding this difference can help them take the correct next step instead of relying on a simple positive or negative test result.
What Does 15 µg/100 cm² Mean?
15 µg/100 cm² Is the Maximum Acceptable Level
Under the 2026 regulations, premises are considered contaminated for residential tenancy purposes when methamphetamine residue is found above 15 µg/100 cm². Areas above this level must be decontaminated according to the prescribed process.
For example:
| Test result | Interpretation |
|---|---|
| 5 µg/100 cm² | Below the maximum acceptable level |
| 12 µg/100 cm² | Below the maximum acceptable level |
| 15 µg/100 cm² | At the maximum acceptable level |
| 18 µg/100 cm² | Above the maximum acceptable level |
| 25 µg/100 cm² | Above the maximum acceptable level |
| 30 µg/100 cm² | At the maximum inhabitable level |
| 35 µg/100 cm² | Above the maximum inhabitable level |
The key point is that 15 µg/100 cm² is the maximum acceptable level under the current residential tenancy rules.
It is not correct to say that a result of 20 or 25 is acceptable simply because it is below 30.
What Does 30 µg/100 cm² Mean?
30 µg/100 cm² Is the Maximum Inhabitable Level
The second important number is 30 µg/100 cm².
Under the 2026 regulations, 30 µg/100 cm² is the maximum inhabitable level for residential tenancy premises. If testing establishes contamination above this level in any part of the premises, the special tenancy termination rules under section 59B of the Residential Tenancies Act may apply, subject to the circumstances and relevant exceptions.
This is different from the 15 µg contamination threshold.
A result above 30 does not simply mean “the contamination is twice as bad”. It crosses a different legal threshold relating to whether the premises can be considered inhabitable for residential tenancy purposes.
This distinction is particularly important when landlords and tenants are deciding how to manage an affected rental property.
15 vs 30 µg: What Is the Difference?
The easiest way to understand the two meth contamination levels is this:
Above 15 µg/100 cm²
The affected area is considered contaminated for residential tenancy purposes.
The area must be decontaminated according to the prescribed process until testing confirms the required level has been achieved.
Between 15 and 30 µg/100 cm²
This is an important middle range.
For example, a result of 22 µg/100 cm² is:
- Above the maximum acceptable level
- Below the maximum inhabitable level
- Still considered contamination under the 2026 residential tenancy rules
- Subject to the applicable decontamination requirements
So below 30 does not mean no action is required.
The two thresholds answer different legal questions:
15 µg/100 cm²:
Is the meth residue above the maximum acceptable level?
30 µg/100 cm²:
Has the residue exceeded the maximum inhabitable level for the purposes of the residential tenancy rules?
These should not be confused.
Does a 20 µg Result Mean the Property Is Acceptable?
No.
A result of 20 µg/100 cm² is below the 30 µg maximum inhabitable level, but it is still above the 15 µg maximum acceptable level.
For residential tenancy premises, the affected area therefore remains contaminated under the regulations and is subject to the applicable decontamination requirements.
This is one of the most important points to understand when reading meth testing results.
For example:
20 µg/100 cm² = above the maximum acceptable level, but below the maximum inhabitable level.
That does not make the result acceptable.
Are Meth Contamination Levels Measured Across the Whole House?
Not necessarily.
The regulations define contamination by reference to methamphetamine being present in any part of the premises above the prescribed maximum acceptable level.
For example, imagine a three-bedroom rental property where testing produces these results:
- Bedroom: 22 µg/100 cm²
- Kitchen: 8 µg/100 cm²
- Bathroom: 11 µg/100 cm²
- Lounge: 6 µg/100 cm²
The bedroom is above the 15 µg/100 cm² maximum acceptable level.
The other tested areas are below it.
This does not automatically mean every room has the same contamination level or requires the same treatment.
A detailed meth contamination assessment can help identify where contamination is present and what areas require decontamination.
If you are concerned about possible contamination, you can also explore the Kiwi Meth Xpert meth testing products and resources.
What Happens When a Property Tests Above 15 µg?
When testing establishes contamination above the applicable maximum acceptable level, the affected areas need to be decontaminated.
The 2026 regulations require the prescribed testing and decontamination process to follow NZS 8510:2017, with the modifications set out in the regulations. Tenancy Services confirms that screening assessments, detailed testing and decontamination must follow the applicable standard and regulatory modifications.
The aim is not simply to make the property look clean.
The important question is whether the affected area has been properly decontaminated and subsequently tested.
This is why property owners should keep testing results and remediation records rather than relying on photographs or ordinary cleaning receipts alone.
For properties requiring professional remediation, Kiwi Meth Xpert’s meth house decontamination services can assist with professional meth contamination cleaning and decontamination.
What Happens After Meth Decontamination?
Decontamination is not automatically complete when the cleaning work finishes.
The 2026 regulations provide for post-decontamination detailed testing. The testing must be carried out independently from the person who carried out the decontamination work.
The purpose is to confirm that the affected areas meet the required level.
If testing shows residue remains above the maximum acceptable level, further decontamination may be required.
This creates an important sequence:
Test → Identify affected areas → Decontaminate → Test again → Confirm results
Property owners should therefore avoid treating cleaning alone as proof that contamination has been resolved.
If you are dealing with contamination after a tenant has moved out, read Meth Cleaning After a Tenant Moves Out: 7 Proven & Safe Steps for additional practical information.
What If the Result Is Above 30 µg?
A result above 30 µg/100 cm² is more significant from a tenancy-law perspective because it is above the maximum inhabitable level.
Tenancy Services explains that where contamination is above 30 µg/100 cm², landlords and tenants may have rights to terminate the tenancy with shorter notice, depending on the circumstances.
This does not mean every tenancy automatically ends.
Landlords and tenants should check the current legislation and Tenancy Services guidance before making decisions about ending a tenancy.
Do the 15 and 30 µg Levels Apply to Every Property?
This is an important distinction.
The Residential Tenancies (Managing Methamphetamine Contamination) Regulations 2026 establish these prescribed levels for the purposes of residential tenancy law.
They should not automatically be described as universal contamination or health thresholds for every building, vehicle or situation in New Zealand.
For example, commercial properties, vehicles and privately owned homes that are not subject to a residential tenancy may require different considerations.
If you are dealing with a rental property, use the current residential tenancy regulations and Tenancy Services information on meth and rental properties as the starting point.
Why Professional Meth Testing Matters
A screening assessment and detailed testing are not necessarily the same thing.
Under the 2026 regulations, landlords must arrange the prescribed testing in certain situations. This includes circumstances where Police or a local authority notifies the landlord that methamphetamine manufacture has taken place or is likely to have taken place, or where a valid screening assessment indicates contamination and the landlord is notified.
Tenancy Services also confirms that testing should follow the applicable requirements of NZS 8510:2017, as modified by the 2026 regulations.
Using the right testing process matters because the result may affect cleaning requirements, tenancy decisions and future property records.
For more information about testing options, visit Kiwi Meth Xpert’s meth testing products and resources.
Common Mistakes When Reading Meth Test Results
Mistake 1: Thinking 30 µg Is the Cleaning Target
It isn’t.
For residential tenancy premises, the maximum acceptable level is 15 µg/100 cm².
The 30 µg figure relates to the maximum inhabitable level.
Mistake 2: Assuming 20 µg Is Acceptable
A result of 20 µg/100 cm² is below 30, but it is still above 15.
The affected area is therefore contaminated under the current residential tenancy rules.
Mistake 3: Assuming a Positive Result Means the Whole Property Is Contaminated
Contamination is assessed based on the applicable testing results from areas of the premises.
One room may have a result above 15 while another area is below the threshold.
Mistake 4: Stopping After Cleaning
Cleaning alone does not confirm that the required contamination level has been achieved.
Post-decontamination testing is an important part of confirming whether further work is required.
Mistake 5: Using Outdated Information
New Zealand’s residential tenancy methamphetamine rules changed on 16 April 2026.
Older articles and advice may refer to previous approaches or thresholds.
For current rental-property requirements, always check the latest Tenancy Services guidance and New Zealand legislation.
How Kiwi Meth Xpert Can Help
Understanding meth contamination levels is the first step. The next step is dealing with the affected property correctly.
Kiwi Meth Xpert provides professional meth testing and decontamination services for properties affected by methamphetamine contamination.
Our services can help property owners understand the contamination issue, identify affected areas and arrange appropriate decontamination.
For properties requiring professional remediation, see our meth house decontamination services for more information about the cleaning and decontamination process.
You can also learn more about meth residue removal and the surfaces that may require specialist attention.
If you are a landlord dealing with contamination after a tenant has moved out, read our meth cleaning after a tenant moves out guide for additional practical information.
Final Thoughts: 15 vs 30 µg
The difference between 15 µg/100 cm² and 30 µg/100 cm² is important.
15 µg/100 cm² is the maximum acceptable level under New Zealand’s 2026 residential tenancy methamphetamine regulations. Areas above this level are considered contaminated for the purposes of the Act and are subject to the applicable decontamination requirements.
30 µg/100 cm² is the maximum inhabitable level. A result above this level can have additional consequences for a residential tenancy, including the application of specific tenancy termination rules, depending on the circumstances.
The most important thing is not to look at a meth test result as simply “positive” or “negative”.
The actual number, location of the contamination, testing method and type of property all matter.
If you receive a meth testing result and are unsure what the numbers mean, use the current New Zealand regulations and Tenancy Services guidance, and consider getting professional advice before starting remediation.
Need help with a meth-contaminated property? Contact Kiwi Meth Xpert to discuss professional testing and decontamination options.
