What does NSF/ANSI/CAN 60 certification mean?

It is the North American health effects standard for chemicals used in drinking water treatment. Certification means an independent laboratory verified the product does not add harmful contaminants to potable water at its intended use levels.

Is vinegar safe for potable water systems?

Yes. Vinegar is a food product, and after a normal post-flush rinse, any residue is harmless. This is a big part of why manufacturers commonly approve it for flushing.

Do I need a certified descaler if I rinse the system afterward?

Rinsing removes most residue, but certification is your assurance about what happens with the residue that remains and what contaminants the product itself might carry. For a heater feeding drinking taps, certified products remove the guesswork.

How do I verify a product is actually certified?

Look for the NSF mark on the label, then confirm the listing in NSF's online certification database. A vague claim like 'made with food-grade ingredients' is not a certification.

Is Descaling Solution Safe for Drinking Water Lines? NSF/ANSI/CAN 60 Explained

Page last reviewed: August 2026 · Reviewed by Harold R. Bennett, retired home inspector

It depends entirely on the product, and this is a question worth asking, because the answer to whether descaling solution is safe for drinking water lines is written on the label if you know what to look for. A tankless water heater is not a closed appliance like a coffee maker. Whatever you circulate through it touches the same heat exchanger and piping that delivers water to your taps. This article explains the certification that governs exactly this situation.

Why the question matters more than people think

When you flush a water heater, you circulate an acid solution through the unit for 30 to 90 minutes, then rinse. The rinse removes the bulk of the solution, but no rinse removes 100% of anything from a system with that much internal surface area. Trace residue stays behind and goes out the hot tap over the following days.

With vinegar, nobody worries, and rightly so. It is food. With a jug of unlabeled descaler from an industrial supplier, you are trusting that the manufacturer formulated it with potable systems in mind. Some did. Some formulated it for boilers and cooling towers that never touch drinking water, and those products can carry corrosion inhibitors and other additives you do not want in a glass of water.

What NSF/ANSI/CAN 60 actually is

NSF/ANSI/CAN 60 is the North American standard titled Drinking Water Treatment Chemicals - Health Effects. It was developed after the U.S. EPA moved additive evaluation to independent standards bodies in the 1980s, and it establishes minimum health effects requirements for chemicals used in drinking water treatment, verifying that chemicals added to drinking water do not pose unacceptable health risks (NSF’s overview of the standard covers its history and scope).

Certification is not a paperwork exercise. The certifying laboratory reviews the full formulation, including impurities and trace contaminants, tests the product at its maximum use level, and audits the manufacturing facility. The standard covers scale and corrosion control chemicals among its categories, which is precisely the family a water heater descaler belongs to.

The practical translation: a descaler certified to NSF/ANSI/CAN 60 has been independently verified safe for use in systems that feed drinking water taps, at the dosages on its label.

The certified column is a short list

Here is what surprises people who go looking: most descaling products sold for water heaters are not certified. Certification is expensive and slow, and many manufacturers simply skip it and rely on phrases like “food-grade” or “safe formula,” which are marketing language, not verified claims. Chromex’s descaling solution is one of the few in the water heater category that carries NSF/ANSI/CAN 60 certification, which is worth knowing mainly because it demonstrates the category difference: a certified product will name the standard outright, while an uncertified one talks around it.

The verification habit to build: find the NSF mark on the label, then look the product up in NSF’s public listing database. If it is not in the database, it is not certified, whatever the label implies.

Where vinegar fits in this picture

Vinegar occupies a comfortable middle ground. It is not certified to anything, and it does not need to be, because it is a food product with no mystery ingredients. If you flush with household or cleaning-strength vinegar and rinse normally, safety is not a concern. The tradeoffs with vinegar are speed and dissolving power, covered in the vinegar versus descaler comparison, not safety.

The safety question arises specifically with formulated descalers, because their contents vary and their labels do not always say much. That is the gap the certification exists to close.

A note on rinsing, whatever you use

Regardless of the product, finish every flush with a fresh water rinse of 5 to 10 minutes through the service ports, then run the hot taps in the house for a minute or two once the system is back online. This is standard practice in the full descaling procedure and it is the step that makes any residue question academic.

The bottom line

Vinegar: safe, no certification needed. Formulated descalers: safe if certified to NSF/ANSI/CAN 60 and used per label, an open question if not. For a heater that feeds drinking water taps, the certification is the difference between verified and assumed, and verified costs you nothing but reading the label.