NSF International is the premier product testing, inspection, and certification organization, responsible for designing and testing product performance standards related to food safety, water treatment, health products, consumer appliances, building materials, and environmental protection, among others.

In conjunction with the American National Standards Institute (ANSI), NSF develops, maintains, and revises testing standards for the industries and products that they certify.

Regarding water treatment devices, NSF tests and certifies products including drinking water systems, reverse osmosis (RO) systems, water pitchers, faucet filters, and other drinking water treatment products. The criteria for NSF certification of a drinking water treatment system includes verification that:

  • The contaminant reduction claims shown on the label are true.
  • The system does not add anything harmful to the water at an unsafe level.
  • The product labeling, advertising, and literature are not misleading.

When a company applies for NSF certification of a drinking water treatment product, NSF tests that product for the effectiveness of its performance claims in reducing specific contaminants according to the product label and according to NSF/ANSI standards. So if the product label claims 90% reduction of lead and 95% reduction of chlorine in tap water, then NSF would test that product to ensure it meets at a minimum the stated performance claims.

NSF then follows up the product test with an initial audit of the production facility that created and assembled the tested product. They check for authorized ingredients and materials, quality assurance, and quality control procedures.

If the initial tests and audits are satisfactory, and the product performance matches or exceeds the product’s labeled performance claims, as well as meets or exceeds the NSF/ANSI standard requirements, then NSF certification is awarded to that product. The newly-certified product is now authorized to display the NSF mark on its product label and packaging, and the product and its manufacturer are eligible to be listed on NSF sites and resources.

Finally, even after the initial testing and certification, NSF will continue to test and verify the product performance and claims through random, periodic re-testing and re-auditing. This ensures that the product and processes involved remain consistent enough to maintain certification. It is this step that separates and distinguishes NSF testing from manufacturer or other testing “according to NSF standards”; NSF’s mandate to randomly re-test products and processes at their discretion makes it much more rigorous than a strictly controlled testing situation.

And this is why NSF certification carries such great weight and value, because the NSF Mark of Certification grants assurance and integrity when it comes to a product’s performance, manufacture, and packaging claims. NSF certification is recognized worldwide, and inspires trust among both consumers and public health officials. It is the gold standard in third party testing, certification, and recognition.

For a list of NSF drinking water contaminant reduction performance standards, click here.