NSF/ANSI/CAN 61 for Coatings
How drinking water coatings are certified to NSF/ANSI/CAN 61, what a listing's conditions mean, and how to keep a tank or pipe project inside them.
Key takeaways
- NSF/ANSI/CAN 61 sets health-effects requirements for products that contact drinking water, including coatings and linings for tanks, pipes and treatment equipment.
- Certification is based on extraction (leaching) testing and toxicological evaluation, not on corrosion or durability performance.
- Every certified coating is listed with conditions — maximum temperature, minimum vessel size or pipe diameter, cure schedule and sometimes film thickness or number of coats. Work outside those conditions is not covered.
- Always verify certification in the certifier’s current online listing, not from a brochure or the word “compliant.”
When a coating is applied inside a potable water storage tank, pipe or treatment structure, regulators want assurance that it will not release harmful substances into the water people drink. In North America the main tool for that assurance is NSF/ANSI/CAN 61, Drinking Water System Components — Health Effects. Most U.S. states require Standard 61 certification for products used in public water systems, and Canadian jurisdictions commonly reference it as well.
This article explains what the standard covers, how coatings are evaluated, how to read a listing and how to keep a project within it. For broader design and application guidance, see potable water tank coatings.
What the standard covers
Standard 61 is an American National Standard maintained through a consensus process administered by NSF. The “CAN” designation was added when it was also adopted as a National Standard of Canada. It applies to components that contact drinking water from the source through treatment and distribution to the tap, including pipes, fittings, valves, process media, joining materials, and barrier materials — the category that includes coatings, linings and liners.
The standard addresses one question: does the product leach contaminants into drinking water at concentrations that could affect health? It does not evaluate corrosion protection, adhesion, abrasion resistance, taste or appearance beyond what is captured in the health evaluation. A coating can be certified and still be a poor choice for a particular tank, so certification is a minimum entry requirement, not a performance endorsement.
The toxicological criteria used to judge test results are now maintained in a companion standard, NSF/ANSI/CAN 600. Lead content of plumbing products is addressed separately by NSF/ANSI/CAN 372.
How coatings are evaluated
- Formulation review. The manufacturer discloses the complete formulation, including raw material suppliers, to the certifier under confidentiality. This determines which contaminants to look for.
- Sample preparation. Test panels are coated and cured following the manufacturer’s stated application and cure conditions, which later become conditions of the listing.
- Exposure (extraction). Panels are exposed to prepared test waters under defined conditions of time, temperature and surface-area-to-volume ratio.
- Analysis. The extraction water is analyzed for regulated contaminants and formulation-specific substances, such as residual solvents, monomers and additives.
- Normalization and toxicology review. Results are normalized to the field use condition, such as a tank of a given size, and compared with allowable concentrations.
- Plant audit and ongoing surveillance. The certifier audits manufacturing, and certified products are periodically retested.
Testing is carried out by ANSI-accredited certification bodies. NSF is the best known, and other accredited certifiers also certify to Standard 61. Their marks and listings carry equal standing where regulators accept accredited certification.
Reading a certification listing
The listing is the legal heart of certification. It names the product and records the conditions under which it was found acceptable. Typical fields include:
| Listing field | What it means | Field implication |
|---|---|---|
| Product and colors | Specific product names, components and colors evaluated | Unlisted colors or components are not certified |
| Water contact temperature | Cold (about 23 °C / 73 °F) or hot-water ratings | Do not use a cold-water listing for hot-water service |
| Minimum size | Smallest tank volume or pipe diameter allowed | Small vessels have more surface per gallon and may not qualify |
| Cure conditions | Time and temperature before water contact | Cold weather lengthens cure; schedule accordingly |
| Coats / thickness | Number of coats or maximum film thickness evaluated | Excess build can retain more solvent |
| Thinner | Whether and which thinner is permitted | An unlisted thinner can void compliance |
| Manufacturing site | Plant(s) whose production is certified | Relevant for imported or relabeled product |
Phrases such as “meets the requirements of,” “formulated to comply with” or “tested to” Standard 61 are not the same as certification. Ask for the listing and check it on the certifier’s website.
Keeping a project within the listing
Most field problems arise not from the product but from how it is used. Practical controls include:
- Specify by listing. State that products shall be certified to NSF/ANSI/CAN 61 for the intended service temperature and minimum vessel size, and require submittals of the current listing.
- Control film build. Measure wet film and dry film thickness, and stay within listed coat and thickness limits.
- Respect cure schedules. Record steel and air temperatures throughout cure. Ventilation, often with forced air and dehumidification, helps remove solvent before filling.
- Use only permitted thinners and cleaners in the coated area, and keep incompatible products out of the tank.
- Disinfect and test. After curing, the structure is typically disinfected per the owner’s procedures, often based on AWWA C652 for storage facilities, and bacteriological sampling is done before return to service.
Odor or taste complaints after return to service often point to incomplete cure or retained solvent. See solvent entrapment and testing coating cure.
Related standards and documents
Standard 61 is usually combined with performance standards. In the U.S., AWWA D102 addresses coating steel water storage tanks, and AWWA C210 and C222 cover liquid epoxy and polyurethane coatings for steel water pipe and fittings. Owners may add their own requirements, and water and wastewater coatings covers the wider service environment. Outside North America, other national schemes apply, such as approvals under the UK’s Regulation 31 system, so check local requirements.
Frequently asked questions
Does NSF 61 certification mean a coating will protect the tank well?
No. It addresses health effects of contact with drinking water only. Corrosion protection, adhesion and durability must be judged separately.
Can I use a certified coating in a small tank?
Only if the vessel meets the minimum size in the listing. Smaller vessels have a higher surface-to-volume ratio, which increases potential leachate concentration.
What if cure temperatures fall below the listed conditions?
Contact the manufacturer and the certifier. Usually the cure period must be extended, or heat must be provided, until listed conditions are met.
Is NSF/ANSI/CAN 61 the same as NSF 61?
Yes. The longer designation reflects its status as both an American and a Canadian national standard.
Educational reference. Coating performance varies by formulation. Always follow the manufacturer’s product data sheet, safety data sheet and your project specification.
