NSF: what brands don’t always explain to you

In the world of water filtration, mentions NSF 42, NSF 53 or NSF P231 are omnipresent. They inspire confidence, but they are also often misunderstood.

The reality is simple: not all filters that say “NSF” are NSF certified.

A common confusion

Many products display:

“Tested to NSF Standards”

But this does not mean:

“NSF certified”

The difference is important.

NSF certified: official validation

A truly NSF certified filter has undergone official validation, with a precise perimeter. Depending on the case, this certification may concern:

• material safety,
• performance on certain contaminants,
• or both.

When a filter is certified, it is not enough to read “NSF 42”: it is also necessary to check what is actually covered.

Tested according to NSF: useful, but different

Many manufacturers use independent laboratories like Envirotek, IAPMO or ASI to perform tests according to NSF protocols.

These analyzes can be serious, detailed and very useful for comparing performance. But they do not replace official certification.

NSF 42 doesn't always mean the same thing

The standard NSF/ANSI 42 concerns the aesthetic contaminants, such as chlorine, taste and odor. However, an NSF 42 filter can be certified:

• either for the materials only,
• either for the performance included.

This nuance changes everything. A product certified for materials does not automatically provide proof of reduction in chlorine, taste or odor.

Why this comparison is useful

The table below makes it possible to clearly distinguish:

• filters truly NSF 42 certified,
• filters simply tested according to NSF standards,
• the laboratories used when they are known,
• the average duration of use,
• and the estimated annual cost.

When it comes to drinking water, precision is better than marketing shortcuts.

Comparison of NSF certifications and tests of the main gravity filters