If you're a licensed plumber in New Zealand, the 1 May 2026 transition deadline under G12/AS1 has now passed — and if you haven't updated your stock and site practices, you could be installing non-compliant fittings without realising it.
Here's what you need to know, what's changed, and how to stay on the right side of MBIE and your building consent authority.
What Is Dezincification, and Why Does It Matter?
Dezincification is a corrosion process that affects certain brass alloys. When water — especially warm, slightly acidic, or chlorinated water common in NZ supplies — flows through standard brass fittings, it can selectively leach the zinc out of the alloy. What's left is a porous, weakened copper matrix that looks fine from the outside but is structurally compromised.
The practical result: fittings that dezincify can eventually fail, causing leaks inside walls, under floors, and in ceiling spaces — often years after installation and well after the plumber has left the job. For the building owner, the consequences range from mould and water damage to structural rot. For you as the installer, the liability exposure is significant.
New Zealand's building stock is particularly vulnerable because of our relatively soft, mildly acidic water in many regions, combined with the large volume of copper and brass hot water systems still in service.
G12/AS1: The Relevant Standard
Clause G12 of the New Zealand Building Code covers water supply systems. The acceptable solution G12/AS1 sets out the specific product requirements plumbers must meet to achieve compliance by right (without needing a specific engineering assessment).
The key update: G12/AS1 now requires that all brass fittings used in water supply installations meet dezincification resistance (DR) requirements, as defined by the relevant AS/NZS standards. The transition period, which allowed plumbers to use up existing non-DR stock, ended on 1 May 2026.
From that date, installing non-DR brass fittings in regulated work is a compliance breach — regardless of when those fittings were manufactured or purchased.
What "Dezincification-Resistant" Actually Means
DR brass is a specific alloy formulation where the zinc content is controlled and trace elements (typically arsenic or antimony) are added to inhibit the dezincification process. In practice, it performs identically to standard brass in normal installation — it's a product-level change, not a technique change.
How to identify DR fittings:
- Look for the "DR" marking stamped or cast directly onto the fitting
- Check for compliance with AS/NZS 1628 (the specification for DR brass)
- Reputable NZ distributors (Reece, Tradelink, Plumbing World) have updated their catalogues — DR-compliant products are now clearly marked online and in store
- Some fittings are marked with a green dot or carry a WaterMark certification that specifies DR compliance — check the WaterMark licence number against the ABCB database if unsure
Non-DR fittings often look identical to DR versions. The only way to be certain is the marking or a verified datasheet from the manufacturer.
What This Means for Your Workflow
Update your van stock now. If you're still running pre-May 2026 stock of standard brass fittings, you need to pull those out of active use for regulated work. They can still be used for non-regulated applications (such as irrigation or some industrial uses), but not in potable water systems covered by the Building Code.
Check your supplier's default product. Some plumbing merchants were already supplying DR fittings by default before the deadline — but don't assume yours was. Ask explicitly. If you've been ordering "standard 15mm elbow" from your usual supplier without specifying DR, it's worth confirming what you've actually been receiving.
Site audits and consent sign-offs. Building consent authorities (BCAs) and MBIE's building inspectors are increasingly checking product compliance at inspection stage. If a fitting can't be confirmed as DR-compliant at inspection, the inspector may require replacement — which means opening walls after the fact. That cost falls on you if the fitting choice was the licensed plumber's call.
Warranty and insurance implications. Your professional liability insurer may take a dim view of claims arising from non-DR fittings installed after 1 May 2026. If you're unsure how your policy handles Building Code non-compliance, it's worth a call to your broker. For a guide on the types of insurance NZ plumbers should hold, see our article on public liability insurance for NZ tradies.
IRD and MBIE: The Compliance Double-Up
One angle plumbers sometimes miss: if a building is inspected and non-compliant work is identified, the BCA may notify MBIE. MBIE has powers under the Building Act to refer matters involving Licensed Building Practitioners — and while plumbers are licensed under their own regime, the principle of compliance with the Building Code as a condition of licence holds.
Separately, IRD's construction sector compliance focus in 2026 means your business records are more likely to be scrutinised. Keeping accurate records of the products you install — including batch numbers for fittings on larger jobs — is not just good practice, it's evidence that you took compliance seriously if a question ever arises. Our NZ tradie tax guide covers the kind of business records that help at both tax time and in disputes.
Pricing the Compliance Cost
DR fittings carry a small price premium over standard brass — typically 5–15% more depending on the fitting type and supplier. On an average bathroom renovation or hot water installation, the difference across all fittings is usually $20–$80 NZD in materials. That's a trivial cost compared to a warranty callback or a failed inspection.
If you're quoting jobs and want to make sure your materials cost is accurate, the plumber pricing guide for NZ 2026 has updated materials cost benchmarks across common residential job types.
Build DR compliance into your quote template as standard — don't offer non-DR as a "cost-saving option." It isn't a saving if it creates liability.
Staying Organised Across Jobs
Managing product records, inspection schedules, and customer sign-offs across multiple active jobs is where a lot of plumbers lose time. Fastcrew is a NZ-built tradie app that lets you attach product details and compliance notes directly to a job — useful when you need to show what was installed and when, especially for warranty and consent purposes.
Free Templates
Download our free NZ tradie templates at tradietools.nz/templates/ — including a job completion checklist that has a product compliance section you can adapt for your G12 sign-offs.
Quick Reference: G12/AS1 DR Fittings Checklist
- Deadline passed: 1 May 2026 — DR fittings required in all regulated water supply work
- Marking to look for: "DR" stamp on fitting, or AS/NZS 1628 compliance
- WaterMark: Confirm DR scope in the WaterMark licence details
- Supplier check: Ask your merchant explicitly if default brass is DR-compliant
- Van stock: Remove non-DR brass from regulated-work use
- Records: Keep product datasheets or batch records for consented work
- Premium: Expect 5–15% materials uplift — negligible vs liability risk
NZ Tradie Tools provides free calculators, templates and guides for New Zealand tradies. Visit tradietools.nz.
Not sure if your quote is fair? Use our free NZ tradie quote checker to compare any quote against typical rates for your city and job type.