When it comes to choosing a water filtration system, many consumers look first and foremost for a well-known and reassuring logo. Among them, NSF certification is often considered the gold standard.
However, a preconceived idea persists: an NSF certified filter would automatically be superior to all others.
The reality is more complex.
NSF certification is indeed an excellent indicator of confidence, but it does not, on its own, make it possible to evaluate the overall performance of a filter or the total number of contaminants studied.
To understand why, it's important to know what NSF certifications actually assess.
The main NSF standards used in water filtration
NSF/ANSI 42: aesthetic effects
This standard mainly concerns:
- chlorine;
- taste;
- odors;
- certain particles.
It mainly aims to improve the comfort of water consumption.
NSF/ANSI 53: health effects
This standard concerns in particular:
- cysts (Giardia, Cryptosporidium);
- lead;
- certain chemical contaminants;
- turbidity.
However, not all NSF 53 certified filters have the same claims.
NSF/ANSI 401: emerging contaminants
This more recent standard covers in particular:
- certain pharmaceutical residues;
- certain pesticides;
- certain herbicides;
- certain emerging compounds;
- microplastics.
NSF/ANSI/CAN 372: lead-free materials
Contrary to popular belief, this standard does not measure filtration performance.
It simply verifies that components in contact with water meet low-lead requirements.
Understanding the concept of “claim”
An NSF certification does not indicate that a filter has been tested against all possible contaminants.
It only validates certain specific claims called “claims”.
In other words, two NSF certified filters can have very different performances depending on the contaminants actually evaluated.
This is why it is essential to look at the details of the certified claims and not just the presence of an NSF logo.
Concrete example: Ultra Sterasyl from British Berkefeld
Ultra Sterasyl is today the main filter used in British Berkefeld gravity systems manufactured by Doulton.
It benefits from several recognized NSF certifications.
According to the official NSF listings, the certified claims are as follows:
| NSF standard | Certified claim |
|---|---|
| NSF 42 | Class I particle reduction |
| NSF 53 | Reduction of cysts |
| NSF 53 | Reduction of turbidity |
| NSF 401 | Reduction of microplastics |
| NSF 372 | Low lead compliance |
Source: official NSF International listings.
What it doesn't mean
Having multiple NSF certifications does not mean that all contaminants have been analyzed or certified.
For example, the NSF claims posted for Ultra Sterasyl do not explicitly cover:
- PFAS;
- fluorides;
- arsenic;
- drug residues;
- pesticides;
- herbicides;
- radionuclides;
- all heavy metals.
This does not mean that the filter is ineffective against these contaminants.
This simply means that these contaminants are not among the certified claims visible in the corresponding NSF listings.
In addition to NSF certifications, Doulton also publishes test results for various contaminants (pesticides, pharmaceutical residues, heavy metals, etc.). According to several sources, these analyzes were carried out by independent, internationally recognized laboratories, based on NSF/ANSI 53 and NSF/ANSI 401 protocols.
Other examples: Coldstream FTO+ and Monderma Imperial GF
The Coldstream FTO+ and Monderma Imperial GF filters perfectly illustrate why it is important not to limit yourself to just the presence of an NSF logo.
Unlike some filters on the market, these filters are not NSF certified. However, this does not mean that they have not undergone rigorous evaluations.
The Coldstream FTO+ filter was notably evaluated by IAPMO, an organization and laboratory recognized internationally in the field of water filtration. The tests were carried out according to NSF/ANSI protocols and cover a wide range of contaminants.
The filter Monderma Imperial GF, manufactured in the United States, is based on comparable technology combining a ceramic shell and activated carbon media. It was the subject of evaluations carried out by Envirotek Laboratories, an independent, internationally recognized laboratory, according to NSF/ANSI 42 and NSF/ANSI 53 protocols.
The results published for these different technologies include analyzes concerning:
- bacteria;
- microplastics;
- PFAS;
- fluorides;
- heavy metals;
- pesticides;
- pharmaceutical residues;
- arsenic;
- many other contaminants.
These examples demonstrate that a filter can be evaluated by an independent, internationally recognized laboratory according to NSF/ANSI protocols without having official NSF certification.
Conversely, an NSF-certified filter can make a smaller number of certified claims while still benefiting fully from the recognition and credibility associated with that certification.
This distinction is essential to understand that NSF certification and testing carried out according to NSF/ANSI protocols are two different but complementary approaches.
NSF certification and laboratory testing: two complementary approaches
NSF certification is an excellent indicator of seriousness.
However, it is only part of the evaluation of a filter.
Manufacturers can also have additional tests carried out by recognized independent laboratories such as:
- NSF International;
- IAPMO;
- Envirotek Laboratories;
- Eurofins;
- Intertek;
- ALS.
These analyzes can cover several dozen, even several hundred contaminants.
They often provide a much more complete view of the real performance of a filter.
Why is the number of contaminants analyzed important?
Current consumer concerns go well beyond simple chlorine or particles.
Today, many people want to know the performance of their filtration system with respect to:
- PFAS;
- microplastics;
- heavy metals;
- pesticides;
- herbicides;
- pharmaceutical residues;
- volatile organic compounds;
- radionuclides.
In this context, detailed laboratory reports become a particularly valuable tool.
A more complete view of performance
Certain market references, such as Black Berkey®, Coldstream FTO+, Monderma Imperial GF® or even the MONDERMA® Imperial AMB® filter, manufactured in the United States, have undergone extensive testing by internationally recognized independent laboratories such as IAPMO or Envirotek Laboratories. Evaluated according to NSF/ANSI protocols, these tests cover a wide range of contaminants and provide a more complete view of filtration performance beyond just certified claims.
These reports do not replace NSF certifications.
They complete them.
They make it possible in particular to identify:
- the number of contaminants studied;
- the reduction rates obtained;
- the test protocols used;
- the concentrations tested;
- the performance observed over the life of the filter.
For this reason, many specialists today consider it relevant to simultaneously examine:
- NSF certifications obtained;
- certified claims;
- the laboratories that carried out the tests;
- the number of contaminants analyzed;
- detailed test results.
How to objectively compare two filters?
To make a serious comparison, it is recommended to examine:
✅ Certifications obtained
✅ The associated certified claims
✅ Test protocols used
✅ The laboratories which carried out the analyzes
✅ The number of contaminants studied
✅ Reduction results published
✅ The concentrations used during the tests
✅ The announced and tested lifespan of the filter
Conclusion
NSF certification remains one of the best indicators of confidence available in the water filtration industry.
However, it should not be considered a single or absolute indicator.
An NSF certified filter is not necessarily superior to one that has been extensively tested by an independent laboratory.
Likewise, two NSF certified filters may have very different performances depending on the contaminants actually evaluated and certified.
The choice of a filtration system must therefore be based on a global analysis taking into account both certifications, certified claims and detailed results of laboratory tests.
When it comes to water filtration, the NSF logo is a great place to start.
But to truly understand the performance of a filter, it is also essential to examine the certified claims, the test reports, the protocols used, the laboratory that carried out the analyzes as well as the number of contaminants actually studied.
The NSF logo provides strong confidence. Detailed test results provide a more complete view of the reality of filtration performance.
Bottom line: NSF certification is a valuable tool, but it's the detailed testing data that lets you understand the full story of a filter.
