When looking at a water filter, you may notice certifications such as NSF/ANSI 42, NSF/ANSI 53 or NSF/ANSI 401.

But what do these numbers actually mean?

NSF standards are used to evaluate drinking-water treatment systems against specific safety and performance requirements. Importantly, the numbers are not rankings — NSF 53 is not simply "better" than NSF 42. Each standard covers different types of filtration claims.

Understanding these certifications can make it easier to compare water filters and choose one suited to your requirements.

What Is NSF/ANSI 42?

NSF/ANSI 42 covers aesthetic effects in drinking water.

This means characteristics that may affect how water looks, smells or tastes rather than contaminants associated with health effects.

Depending on the individual filter's certified claims, NSF 42 can include reduction of:

• Chlorine
• Taste and odour
• Particulates
• Chloramine
• Other aesthetic-related substances

A filter carrying an NSF 42 certification should still be checked for its individual reduction claims, as not every filter certified under the standard is certified for every possible claim.

What Is NSF/ANSI 53?

NSF/ANSI 53 covers filtration claims involving contaminants with potential health effects.

The standard includes numerous possible reduction claims, including substances such as lead and certain cysts.

Again, NSF 53 certification does not mean that a filter removes every contaminant covered by the standard.

Instead, the certification applies to the particular claims that were tested and certified for that product.

For example, an individual filter may be certified under NSF 53 for lead reduction, while another filter may carry certification for a different set of contaminants.

What Is NSF/ANSI 401?

You may also see NSF/ANSI 401 on newer filtration products.

NSF describes Standard 401 as covering emerging compounds and incidental contaminants that may occur in drinking water at trace levels.

The standard includes a range of specific contaminant-reduction claims, depending on the filtration product.

For example, the Pentair Everpure 4FC-PS is certified under NSF/ANSI 401 specifically for microplastics reduction. It also carries NSF/ANSI 42 and 53 certifications for other specific reduction claims.

Does More NSF Certification Mean a Better Filter?

Not necessarily.

The correct filtration system depends on what you need the filter to do.

A filter used for improving drinking-water taste may have very different requirements from one used for a coffee machine, ice machine or commercial kitchen.

Instead of looking only at the certification number, check:

• Which contaminants the filter is certified to reduce
• Filtration capacity
• Flow rate
• Micron rating
• Intended application
• Replacement requirements

NSF itself recommends checking both the standard and the specific contaminant-reduction claim when evaluating a certified filtration product.

NSF-Certified Everpure Filters

Pentair Everpure filters supplied by GFS Innovation are certified under NSF/ANSI standards.

For example, the Everpure 4FC-PS carries certifications under NSF/ANSI Standards 42, 53 and 401 for specific claims including chlorine taste and odour, particulate, lead, cyst and microplastics reduction.

Other Everpure cartridges are designed specifically for applications such as coffee machines, ice machines, drinking water and foodservice equipment.

This is why choosing a water filter should start with understanding the application rather than simply choosing the cartridge with the longest list of features.

GFS Innovation supplies Pentair Everpure filtration systems for residential, office, F&B, hospitality and commercial applications in Singapore.

Our team can recommend a filtration setup based on your equipment, usage requirements and intended application.