Comparison of water filters: NSF certifications, laboratory tests and contaminants analyzed
The NSF certification constitutes a real guarantee of seriousness. It means that a product, material or performance has been evaluated according to precise requirements by an independent organization.
However, it does not mean that a filter automatically eliminates all contaminants present in the water. Each manufacturer chooses the performances, called claims, that it wishes to have tested or certified. Two filters bearing NSF certification can therefore have very different filtration capacities.
1. Check the scope of NSF certification
An NSF certification is an important indicator of quality and reliability, but it only covers the standards, performance and contaminants included in the certificate.
For example, the standard NSF/ANSI 42 mainly concerns the aesthetic effects of water, such as chlorine, taste or smells. The NSF/ANSI 53 standard concerns certain substances that may have an effect on health, such as lead or other specifically claimed contaminants.
The presence of certification therefore does not mean that all of the contaminants covered by a standard have been tested. It is necessary to check the exact performance mentioned on the certificate.
2. View selected analyzes and contaminants
Test reports allow you to understand precisely what was analyzed. In particular, it is necessary to look at:
- the selected contaminants or parameters;
- the concentrations measured before and after filtration;
- the reduction rate obtained;
- the volume of water used during the tests;
- the laboratory which carried out the analyses;
- the protocols and standards applied.
A filter tested on a large number of contaminants can provide a more complete vision of its performance than a product certified for only a few claims. However, the number of elements analyzed is not enough in itself: it is also necessary to verify the relevance of the contaminants chosen and the results obtained.
3. Examine the quality and benefit of filter media
The internal composition of the filter plays an essential role in its performance. Each media has different properties:
- block activated carbon promotes prolonged contact with water and can reduce chlorine, tastes, odors and many organic compounds;
- granular activated carbon offers a large adsorption surface and generally smoother flow rate;
- ceramic microporous constitutes a mechanical barrier against particles, sediments and certain microorganisms depending on its filtration fineness;
- zeolite can participate in the retention or exchange of certain ions and metals;
- ion exchange resins are used to target certain specific substances ;
- the silver integrated into the media can help limit bacterial development inside the filter, depending on its design.
The quality, quantity and combination of these media directly influence the flow rate, water contact time, filter life and contaminants that can be reduced.
| Filter / Brand | NSF certification | Tested according to NSF/ANSI 42 | Tested according to NSF/ANSI 53 | Laboratory | Items analyzed |
|---|---|---|---|---|---|
| 🥇 Mondema Impérial AMB | ✓ | ✓ | ✓ | Envirotek Inc. (USA) | 200+ elements analyzed |
| 🥇 Monderma Impérial GF | ✗ | ✓ | ✓ | Envirotek Inc. (USA) | 200+ elements analyzed |
| Coldstream FTO+ | ✗ | ✓ | ✓ | IAPMO R&T (USA) | 200+ elements analyzed |
| Coldstream CTO+ | ✗ | ✓ | ✓ | Envirotek Inc. (USA) | 100+ items analyzed |
| Black Berkey | ✗ | ✓ | ✓ | Envirotek Inc. (USA) | 200+ contaminants analyzed |
| Phoenix Gravity | ✓ | ✓ | ✗ | NSF / independent laboratories | 150+ elements analyzed |
| Monderma Black Filters | ✓ | ✓ | — | Independent laboratory | Data on request |
| Doulton / British Berkefeld | ✓ | ✓ | ✓ | Organizations and laboratories independent | According to models and certificates |
| Fontaine EVA | ✗ | — | — | CARSO / COFRAC according to analyses | According to published analyses |
Tested according to NSF/ANSI 42 or 53: means that tests have been carried out according to the protocols of these standards by a laboratory. A product can be tested to a standard without having official NSF certification.
Claims: performances or reductions in contaminants selected and claimed by the manufacturer as part of a certification or test report.
Elements analyzed: number of parameters, substances or contaminants included in the available reports. This number must always be interpreted with the results obtained, the test conditions and the relevance of the selected contaminants.
Filter media: the quality and combination of activated carbon, ceramic, zeolite, resins or other materials influence the performance, flow rate, lifespan and type of contaminants that can be reduced.
Table provided for informational and comparative purposes. Certifications, test reports and performance may vary depending on models, filter generations and claims selected by each manufacturer. It is recommended to consult the most recent certificates and technical reports before any publication or purchasing decision. Last updated: July 2026. The brands mentioned remain the property of their respective owners.
