Discover how water filters are tested and certified, and why this kind of third-party verification is critical.

CLEAN WATER, PROVEN PERFORMANCE

Filter Testing and Certification

At Clearly Filtered, we believe clean water should come with complete confidence. That’s why our filters undergo rigorous testing and third-party certification so you know they meet (and exceed) the highest industry standards. Discover how testing and certification work and why it matters for your water.

National Sanitation Foundation

Water Quality Association

International Association of Plumbing & Mechanical Officials

Who Can Grant Certifications?

**No, and the difference matters.**

## **At-Home Tests**

Services like MyTapScore rely on self-collected samples to provide a snapshot of your current water quality. From sampling errors to preservation issues during shipping, at-home tests often lack the precision and reliability of professionally controlled tests that start and end in a laboratory.

## **Controlled Tests**

In addition to eliminating any human error or shipping issues, accredited labs follow standardized protocols and use calibrated equipment to produce repeatable results. That's why every Clearly Filtered product is tested in one.

**Understanding Testing vs Certification**

When evaluating water filters, it’s important to understand the difference between testing to NSF/ANSI standards and obtaining NSF certification

**What "Tested to NSF Standards" Really Means**

Testing to NSF/ANSI standards means an independent lab evaluates a filter’s performance using NSF/ANSI testing protocols.This process measures contaminant reduction, flow rate, and durability under controlled conditions, but it does not result in official NSF certification.

**What NSF Certification Involves**

NSF Certification includes additional steps such as material safety reviews, structural integrity testing, and manufacturing facility audits to verify consistent filter quality–all done by an entity accredited to certify. If a filter meets all requirements, it earns the NSF seal, signifying official certification.

Testing to NSF Standards vs. NSF Certification

Independent labs evaluate a filter’s performance using NSF/ANSI testing protocols, measuring contaminant reduction, flow rate, and durability. However, this testing does not result in official NSF certification.

NSF Certification goes beyond product testing to include material safety reviews, structural integrity testing, and manufacturing facility audits to verify consistent filter quality and performance.

**NSF/ANSI 42:**

Focuses on improving the taste, smell, and appearance of your water by reducing contaminants like chlorine.

**NSF/ANSI 53:**

Focuses on the reduction of harmful contaminants that can pose serious health risks.

**NSF/ANSI 372:**

Verifies compliance with lead content requirements by establishing a standardized method for ensuring filters meet the definition of "lead-free."

NSF/ANSI Standards We Meet

Manufacturers initiate the process by submitting a formal application to the certification body, expressing their intent to have a filter certified.​

Detailed documentation is provided, including filter design specifications, materials used, and intended performance claims.​

The certification body's technical team conducts a thorough evaluation of the submitted information to ensure compliance with relevant standards.​

The certification body’s inspectors perform an on-site audit of the manufacturing facility to assess production processes and collect water samples for testing.​

Collected samples undergo rigorous testing in accredited laboratories to verify performance claims, material safety, and structural integrity.

A comprehensive review of all gathered data is conducted to confirm that the filter meets all certification requirements.​

Upon successful completion of the evaluation, the certification body grants certification, allowing the manufacturer to use the accredited body’s mark and have the filter listed on their official website as meeting the relevant NSF/ANSI standards evaluated.

The Testing Process

The highest level of contaminant reduction measured across the filter’s full lifespan. 

The reduction levels averaged across all data points throughout the testing period. 

How well the filter performs as it nears the end of its usable life.

**Max Reduction Rate**

The highest level of contaminant reduction measured across the filter’s full lifespan.

**Average Reduction Rate**

The reduction levels averaged across all data points throughout the testing period.

**End-of-Life Performance**

How well the filter performs as it nears the end of its usable life.

Clearly Filtered uses certified lab testing to ensure filter reliability and help customers understand how external factors can affect filter performance.

**Lab Conditions**

Testing is conducted in controlled environments using clean water spiked with contaminants at specific concentrations.

**Real-World Conditions**

Real-world water comes from public water supplies and already contains a mix of contaminants that can affect filter performance.

Testing is conducted in controlled environments using clean water spiked with isolated contaminants at specific concentrations.

Real-world water comes from public water supplies & already contains a mix of contaminant that can affect filter performance.

Factors like hard or highly contaminated tap water, reduced water flow, heavy usage, and changes in taste may affect the filter's lifespan. If your water has more to capture, your filter will work harder and may slow down sooner than expected—a sign the filter is doing its job.

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Understanding Our Filter Performance Metrics

**Many brands focus solely on max reduction rates to highlight the best possible performance. While impressive, these numbers don’t always reflect real-world performance over time.**

We're sharing _average_ reduction rates to give a more realistic picture of how our filters perform over the life of the product and help you make more informed decisions about when to replace them.

Keep reading to learn more about how testing and certification work and why it matters for your water.


How & Why We Test

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Testing vs Certification

Clearly Filtered products remove tap water contaminants like Fluoride, Lead, Mercury, Arsenic and Chromium-6 by up to 99.9%. Get cleaner water today

Filter Testing and Certification

Tested vs. Certification

Are All Labs & Tests Created Equal?

At-Home Tests

Controlled Tests

Testing to NSF Standards vs. NSF Certification

Filter Performance

Certified by Experts, Chosen by Families

How & Why We Test

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