WRAS and ACS: Drinking-Water-Safe Powder Coatings

When a powder coating contacts drinking water – pipes, fittings, valves, storage tanks – it becomes a food-contact material in every practical sense. The coating must not leach harmful substances or taint the water. That is why national approval schemes exist, and why buyers should never accept a coating without the right certificate.

Why Water-Contact Coatings Are Different

A coating in drinking water service is tested for what it releases, not just how it performs. Migrated metals, organic compounds and changes to taste or odor are all measured. A coating can be perfect in salt spray and still fail water approval, so the two requirements are completely separate.

WRAS, ACS and NSF 61

• WRAS: the UK approval covering materials in contact with public water supplies
• ACS: the French health ministry approval with its own migration and taste tests
• NSF 61: the US standard for drinking water system components
• Each is issued for specific products and colors – check your exact item is covered

Which Systems Are Approved

Epoxy and epoxy-based systems dominate drinking water approvals because they cure into a dense, low-migration film with excellent adhesion to steel and ductile iron. Fusion-bonded epoxy (FBE) is the workhorse for pipe interiors and fittings. Polyester and polyurethane can also be approved for specific uses, but epoxy is the safe default for water contact.

Specifying for Water Service

• Request the WRAS/ACS/NSF certificate and verify the product name, color and batch coverage
• Specify cure conditions that guarantee a fully cured film – under-cured epoxy migrates more
• Set a minimum film thickness to avoid pinholing and bare spots
• Keep the certificate in your records for audits and end-customer requests