Checking Water Filter Claims for PFAS and Other Contaminants

How to verify independent certifications for water filter performance

Feb. 28, 2026 at 10:36am

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With concerns about PFAS, lead, and other contaminants in drinking water, a new generation of water filters are making bold claims about reducing these pollutants. However, verifying the credibility of these claims can be challenging. This article provides a guide on how to check for independent third-party certifications, such as those from NSF/ANSI, to assess the performance of water filters in removing various contaminants.

Why it matters

As the EPA works to set new federal limits on PFAS and other emerging contaminants, many consumers are turning to water filters to ensure their drinking water is safe. Understanding how to properly evaluate water filter claims is crucial to making an informed purchase that will effectively protect your health.

The details

The article explains that vague claims from water filter manufacturers are harder to trust without clear evidence of independent third-party testing. The most reliable certifications come from organizations like NSF International, a nonprofit that develops standards and verifies adherence for water filters. There are three main NSF/ANSI standards that apply to home drinking water filters: NSF/ANSI 42 for aesthetic effects, NSF/ANSI 53 for health effects, and NSF/ANSI 401 for emerging contaminants. Filters that are certified to these standards have undergone rigorous testing to validate their performance claims.

  • The EPA announced in 2026 that up to 10% of US water systems may have unsafe PFAS levels.
  • New federal PFAS and PFOA limits for drinking water won't take effect until 2031.

The players

NSF International

A Michigan-based, nongovernmental nonprofit founded in 1944 that develops and verifies adherence to standards for water filters and other products.

American National Standards Institute (ANSI)

An independent nonprofit that accredits accreditation and testing organizations like NSF International.

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What they’re saying

“Vague claims of 99 percent reduction in chlorine or PFAS or arsenic are harder to trust if the testing is internal to the company itself.”

— Matthew Korfhage, Author

What’s next

As the EPA works to set new federal limits on PFAS and other emerging contaminants, consumers will need to continue monitoring developments and verifying water filter claims to ensure their drinking water remains safe.

The takeaway

Understanding how to properly evaluate water filter certifications, such as those from NSF/ANSI, is crucial for consumers to make informed purchases that will effectively protect their health from contaminants like PFAS, lead, and heavy metals in the water supply.