Potable-Water Butterfly Valves: NSF/ANSI 61 & 372, WRAS, ACS and WaterMark Explained
Written by
Allen Zhang · Senior Application Engineer, LAUX VALVE
A butterfly valve on a drinking-water main has to do more than seal — every wetted surface it presents to the water must be certified safe to touch potable water and low enough in lead to meet the law. A valve that is mechanically perfect but lacks the right approval will be rejected at inspection, and in some jurisdictions installing an uncertified valve on a public supply is illegal. This guide explains the approvals that matter — NSF/ANSI 61 and 372 in North America, WRAS in the UK, ACS in France, WaterMark in Australia — what each actually certifies, the materials a potable valve must use, and a selection flow so the valve you specify is compliant as well as correctly sized.
The approvals and what each certifies
| Approval | Region | What it certifies |
|---|---|---|
| NSF/ANSI 61 | North America | Wetted materials don't leach harmful substances into water |
| NSF/ANSI 372 | North America | Lead-free: ≤0.25% weighted-average lead on wetted surfaces |
| WRAS | United Kingdom | Material/product safe & compliant with UK water regs |
| ACS | France | Attestation de Conformité Sanitaire for potable contact |
| WaterMark | Australia | Conformance with Australian plumbing standards |
What a potable-water valve is made of
A compliant potable valve is a resilient-seated design where every wetted part is chosen for both water safety and low lead. The seat is a potable-grade EPDM compound — EPDM is ideal for water, and certified grades are tested to leach nothing harmful. The body is ductile iron fully lined with a food-grade, lead-free epoxy so the water never touches bare iron. The disc is stainless steel (often CF8M/316 or 316L), and the shaft, bearings and fasteners must also be lead-free, water-safe materials. The crucial point is that certification applies to the specific compound and coating recipe, tested as a finished product — not to the generic material name. Two valves can both say EPDM and only one hold the certificate.
Selecting a compliant potable-water valve
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1. Identify the required approval
Find which mark the local water authority and project spec demand — NSF/ANSI 61 & 372, WRAS, ACS or WaterMark. This is jurisdiction-driven and must be confirmed before sizing anything.
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2. Demand the certificate, not a claim
Ask for the actual listing/certificate number and the certifying body, and verify it on the certifier's online database. A line in a brochure saying 'EPDM, suitable for potable water' is not certification.
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3. Confirm every wetted part is covered
The certificate must cover the seat, the body lining, the disc and the shaft — not just one component. A lead-bearing shaft or an uncoated body spot can fail the whole valve on a 372 lead test even with a certified seat.
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4. Choose body style and pressure rating
For buried mains and large transmission lines a double-flange (often AWWA C504) valve suits; wafer or lug serve plant and building water. Match the PN/Class to the network pressure as you would any water valve.
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5. Document the certificate in the O&M file
File the certificate numbers in the project documentation so the inspector and the water authority can verify compliance now and at any future audit. Undocumented compliance is the same as non-compliance at handover.
Frequently asked questions
What is the difference between NSF/ANSI 61 and NSF/ANSI 372?
They are complementary. NSF/ANSI 61 is the health-effects standard: it tests that the wetted materials of a valve do not leach harmful contaminants into drinking water at unsafe levels. NSF/ANSI 372 is the lead-content standard: it confirms the weighted-average lead across all wetted surfaces is at or below 0.25%, the 'lead-free' limit set by US law. A fully compliant potable valve carries both — 61 proves it is non-toxic in service, 372 proves it meets the lead law. Some certificates list them together (often shown as 'NSF 61-G' or '61/372'); always confirm both are covered.
Is EPDM safe for drinking water?
Yes, when it is a potable-grade, certified EPDM compound. EPDM is an excellent base material for water — it resists water, ozone and weathering and is the standard seat for water service — but only specific compounds are formulated and tested to be safe for drinking-water contact and certified to NSF/ANSI 61, WRAS, ACS or the relevant scheme. An ordinary industrial EPDM seat is not automatically potable-safe; it may contain fillers or processing aids that leach. Always specify the certified potable grade and confirm the certificate, rather than assuming any EPDM seat qualifies.
Does the valve body need to be coated for potable water?
If the body is ductile or cast iron, yes — it must be fully lined with a certified food-grade, lead-free epoxy so the water never contacts bare iron, which would corrode and discolour the water. The coating itself must be certified to the same potable standard as the seat, applied to the right film thickness with no holidays (uncoated spots). Stainless-steel-bodied valves (CF8M) don't need a lining because the metal is already water-safe, but they cost more. The common, economical compliant build is a certified-epoxy-lined ductile-iron body with a stainless disc and a potable EPDM seat.
Can I use the same butterfly valve for potable water and fire protection?
Only if it carries both sets of approvals, and that is the key. A fire-protection valve must be UL/FM listed and supervised; a potable valve must hold NSF/61 & 372 (or WRAS/ACS) for water safety. Where a sprinkler system is fed from the potable supply — common in buildings — the control valve at the tie-in often needs to satisfy both: listed for fire service and certified for potable contact. Valves built and certified for this dual duty exist, but you cannot assume a fire valve is potable-safe or a potable valve is fire-listed; confirm both certificates explicitly on the data sheet before specifying one valve for both roles.
