WATER SERVICES

DR brass and dezincification in Victorian water

Dezincification is zinc slowly leaching out of brass, leaving behind a weak, porous metal that fails. Where the water chemistry encourages it, the fix is dezincification-resistant brass, and you need to be able to prove the fitting is rated for it.

What dezincification actually is

Dezincification is a form of corrosion that attacks ordinary brass. The zinc in the alloy slowly leaches out and leaves behind a soft, porous copper-rich layer. The fitting can look fine from outside while it is losing strength, then it cracks, weeps, or blocks with white corrosion product. It is a slow failure, which is what makes it dangerous: the work passed when you left, and the problem turns up years later.

Where DR brass is needed

Dezincification-resistant (DR) brass is brass made to resist that zinc loss. It is used where ordinary brass would be at risk, particularly on fittings in continuous contact with water in an aggressive supply. The standard sets out where DR-rated fittings are required, so check the current standard for the specific application rather than carrying one rule everywhere. The common failures are using a non-DR fitting in a spot that calls for DR, and mixing the two without realising it.

Why local water chemistry matters

Whether brass dezincifies depends heavily on the water it carries. Some Victorian supplies are far more aggressive to ordinary brass than others, so a fitting that lasts for years in one town can fail much sooner in another. If you work across different supply areas, do not assume what held up on the last job will hold up on this one. Where the local supply is known to be aggressive, DR brass removes the question.

Confirming and recording the rating

• Check the fitting for the DR marking and read it against the manufacturer's product data, not just the look of the brass.
• If you cannot confirm the rating, treat the fitting as not DR.
• Photograph the fitting and its markings so the rating is on the record, not just in your memory.

Common questions

How do I know a brass fitting is dezincification-resistant?

Look for the DR marking on the fitting and confirm it against the manufacturer's product data. Do not assume a fitting is DR just because it is brass. If you cannot confirm the rating, treat it as not rated and check the current standard for where DR is required.

Why does the local water matter for dezincification?

Water chemistry drives the reaction. Some supplies are far more aggressive to ordinary brass than others, so the same fitting can last for years in one area and fail in another. Where the supply is known to be aggressive, DR brass is the safe call.

General information for licensed tradespeople, not legal or regulatory advice. The licensed plumber remains solely responsible for compliance. Refer to the current AS/NZS 3500 standards and the Building and Plumbing Commission (formerly the VBA) for authoritative requirements.