NSF 61

Definition and Purpose (Health Effects for Drinking-Water Contact)

NSF/ANSI/CAN 61 (often abbreviated as “NSF 61”) is a North American consensus standard for products and components that come into contact with drinking water. It is used in the United States and Canada when the question is whether a material or a component can release substances of health relevance into drinking water. At the center are “health effects” — that is, possible effects on health from chemical substances that transfer from materials into the water.

The standard mainly considers migration or leaching: this means that constituents of a material (for example additives, processing aids, or degradation products) transfer from the solid into the water. The technical basis is an extraction test. In this test, a product is brought into contact with water under defined conditions, and the resulting extraction water is then analyzed and evaluated toxicologically. The goal is a traceable minimum requirement for health safety in the intended drinking-water contact.

What the Standard Covers — and What It Does Not

NSF 61 addresses chemical contaminants that can arise from material contact. From this, the conclusion is frequently — and incorrectly — drawn that a product is overall “better” or “of higher quality”. The standard supports this conclusion only to a limited extent, because it primarily evaluates substance migration and is not a comprehensive performance standard covering all properties of a product.

Another common misconception concerns “lead-free”. In practice, the lead content as a material parameter is often considered separately, because NSF/ANSI/CAN 372 is used as the specific verification path for this. NSF 61, by contrast, remains at the level of leaching and health assessment in drinking-water contact.

Scope and Relevance for Sealing and Plastics Technology

NSF 61 is relevant for many product categories in drinking-water systems. These also include “joining and sealing materials” — that is, joining and sealing materials — as well as mechanical devices such as valves, water meters, or filters. For sealing technology, this is particularly important, because seals frequently consist of polymer-based recipes and can therefore contain several potential sources of migrating substances.

In polymeric materials, migration often arises not only from the base polymer fraction but from recipe ingredients such as plasticizers, cross-linkers, stabilizers, pigments, or processing residues. Aging products can also play a role when a material is chemically or thermally stressed under drinking-water conditions. NSF 61 therefore evaluates not only “what is in the material” but, above all, what actually transfers into the water under defined water contact.

Typical Components and Material Groups

In practice, NSF 61 frequently concerns the following components and material groups:

• Seals and diaphragms made of elastomers (e.g., for fittings, valves, backflow preventers)
• Housings, inserts, pipe and connection parts made of plastics (e.g., in filters, manifolds, couplings)
• Fluorinated materials such as fluoropolymers and fluoroelastomers, when used in drinking-water components

Relevance rises when large wetted surfaces, long contact times, or elevated temperatures are present. Seals in particular are frequently small but permanently wetted. As a result, the topic of leaching becomes a recurring question in material selection across many applications.

Testing and Verification Logic: Extraction Test, Assessment, and Certification

The conformity assessment according to NSF 61 follows a clear logic: a product is brought into contact with water under specified conditions, and the resulting extraction water is then analyzed for relevant substances. After this, a toxicological classification follows on whether the measured concentrations fall within the normative acceptance criteria. As a result, not only a theoretical recipe status is evaluated but a practice-oriented release behavior under water contact.

For users in sealing technology, it is decisive that the result refers to the defined operating range. Changes to the recipe, manufacturing process, or geometry can influence the leaching behavior. Therefore, in certification processes, not only measured values are frequently considered, but also formulation data and boundary conditions such as temperature, contact area, and application category.

“Certified” vs. “Tested To”

A test report saying “tested to NSF 61” can provide a snapshot but often says less about a permanently secured conformity. A certification usually means an independent third-party process, in which test data, recipe/formulation information, and defined operating conditions are evaluated together. This matters in many drinking-water projects, because tenders or regulatory requirements frequently demand an accredited third-party certification explicitly.

The distinction can be summarized in a practice-oriented way as follows:

Distinctions and Current Developments (NSF 372, PFAS Updates)

In drinking-water applications, NSF 61 and NSF 372 often appear together, because they answer different but complementary questions. NSF 61 clarifies whether substances from the product transfer into the water in amounts of health relevance. NSF 372, by contrast, classifies the lead content of a product, which is a separate verification path in many “lead-free” regimes.

In parallel, PFAS-related requirements are gaining importance. For certain fluorinated materials, additional PFAS test requirements have been added in more recent editions of NSF 61. In this context, a transition period until January 1, 2028 is cited. For sealing technology, this is mainly relevant where fluoropolymers or fluoroelastomers are used because of their media and temperature resistance.

NSF 61 vs. NSF 372 (Lead Content)

NSF 61 and NSF 372 are frequently mentioned together in specifications, because both play a role in the drinking-water context. In terms of content, however, the focus areas remain clearly separated: NSF 61 evaluates the release of substances into drinking water and their health relevance. NSF 372 considers the lead fraction as a material parameter in the sense of “lead content”.

PFAS: Relevance for Fluorinated Materials and Transition Period

PFAS requirements mainly concern applications in which fluorinated polymers or elastomers are used. The extension of the test requirements in NSF 61 aims to better reflect PFAS-related risks in drinking-water contact. For implementation, a transition period until January 1, 2028 is cited, which can influence material decisions, requalifications, and documentation chains.

In the end, a practical consequence remains in many projects: with drinking-water contact, material selection, recipe changes, and documentation should be coordinated early. Specialized technical consultation can help to reduce testing and approval risks.