3 Sep, 2026

Drinking Water Compliance for Seals: AS 4020 and WaterMark

AS 4020 and WaterMark both turn up on drinking water compliance checklists, and it’s easy to reach for the wrong one. Supply an AS 4020 test report when the spec called for WaterMark, and the order sits waiting while the right paperwork gets sorted out.

Here’s how to tell the two apart and know which one your project actually needs, before it becomes a problem on site.

Quick Answer

• AS4020 drinking water testing assesses a material’s safety for contact with potable water, including taste, appearance, and chemical leaching.
• WaterMark certification applies to plumbing and drainage products listed under the WaterMark scheme. Where those products contact drinking water, compliance with AS/NZS 4020 forms part of the evidence required.
• A seal can be cut from AS 4020-tested rubber without the finished product needing WaterMark, depending on what it’s installed into.
• AS/NZS 4020-tested EPDM and silicone are common choices for potable water sealing applications.

Why the Two Get Mixed Up

Both terms show up on the same spec sheets, both relate to drinking water safety, and both are issued by accredited bodies. The difference comes down to what’s being assessed: a material property or a finished product.

AS/NZS 4020 answers the question: Does this material or product meet the required tests for contact with drinking water? 

WaterMark answers a different question: “Is this finished plumbing product legally allowed to be installed?” A gasket can pass the first test and still not need the second, if it’s a component rather than a standalone plumbing product.

What AS4020 Drinking Water Testing Actually Checks

The AS/NZS 4020 standard requires materials to be tested for taste, odour, appearance, growth of aquatic micro-organisms, and metal or chemical leaching. It applies to pipes, fittings, and jointing or sealing materials used across the water supply industry.

For gasket buyers, this is the certificate to ask for whenever AS4020 drinking water compliance is the actual benchmark, rather than assuming a separate certification automatically covers material safety. It’s the material itself being assessed, not the finished fitting that ends up inside.

What WaterMark Certification Actually Requires

WaterMark is administered by the Australian Building Codes Board and applies to products listed on the WaterMark Schedule of Products. These are things like tapware, valves, and pipe fittings that a licensed plumber installs directly. Certification runs on a five-year cycle with annual audits, and installing a listed product without it isn’t legally permitted.

WaterMark certification is at the finished-product level, not the raw-material level. Raw gasket material generally isn’t itself a listed product under the Schedule. Instead, the WaterMark obligation applies to the finished product of which it forms part, such as a valve, fitting, or tank connection.

Three Questions Worth Asking Before You Order

• Is the seal a standalone component, or part of a finished plumbing product that needs to be installed by a licensed plumber?
• Does your supplier hold current AS 4020 test documentation for the specific material and thickness you’re ordering, not just the general compound?
• If the finished assembly requires WaterMark, has the product manufacturer already secured that certification?

Materials That Suit Drinking Water Contact

AS/NZS 4020-tested EPDM rubber gaskets and EPDM sheet are widely used in Australian water infrastructure because they perform well against water, weathering and ozone exposure. Silicone rubber sheet is the better option where the application also requires higher-temperature performance.

As a trusted rubber gasket supplier, Industrial Experts can confirm current AS 4020 documentation for the material and thickness your project needs before you place an order.

Sourcing Compliant Seals from Industrial Experts

Industrial Experts cuts AS 4020-tested EPDM and silicone gasket material to size from our Truganina, Melbourne facility. Our full range of industrial seals and gaskets covers everything from water infrastructure through to general industrial sealing, and our team can talk through material selection before you commit to an order.

Orders ship nationally, with delivery generally fastest in Victoria and slower the further you are from Melbourne, particularly Western Australia and the Northern Territory. Exact timeframes depend on your location, stock availability, and the courier network at the time of order, so it’s worth confirming with our team when you request a quote.

If a project needs both material-testing evidence and clarity on whether WaterMark applies, tell us what the finished product is, and we’ll help you determine which certifications you actually need.