How to Read a Water Filter Certification Listing

The standards you will see

The EPA's WaterSense guide and the CDC both list these standards and advise matching the certification to your treatment goal.

Step by step: reading a listing

1. Find the certifier. NSF runs a public database of certified drinking water treatment units. Other accredited certifiers publish their own listings.
2. Search the exact model number. Similar names are not the same product.
3. Check the standard. A system certified only to NSF/ANSI 42 is certified for aesthetic claims, not health-related reductions.
4. Read the claims list. Each listing names specific contaminants or effects. If yours is not listed, the product is not certified for it.
5. Check the replacement cartridge. Listings usually name the cartridges that keep the claim valid.
6. Check capacity. Many claims apply up to a rated volume or service life.

Common mistakes

• "Tested to" or "meets" a standard is not the same as "certified to" it by a third party.
• Certification of one component, such as the membrane, is not certification of the whole system.
• A whole-home system's listing and an under-sink model's listing can differ even from the same brand.
• Claims expire if you use a non-listed replacement cartridge.

Matching claims to your goal

Start with what you want to change. For chlorine or chloramine taste and odor, look for the specific claim; the chloramine guide explains why the two differ. For PFAS, the EPA points to NSF/ANSI 53 or 58 certification for PFOA/PFOS reduction; see verifying PFAS claims. For lead, see the lead testing and filter guide.

A quick example

Say a city-water customer wants less chloramine taste at every tap and also wants better drinking water at the kitchen sink. For the whole-home side, they would look for a model whose listing includes a chloramine reduction claim, not only a chlorine claim. For the kitchen, they would look for an RO system certified to NSF/ANSI 58, and check that any extra claim they care about appears on that same listing. Two products, two listings, two separate checks. Neither listing says anything about the other product, and neither covers a contaminant that is not named on it.

The performance data sheet

Certified products come with a performance data sheet listing the contaminants reduced, test conditions and capacity. The EPA's WaterSense guide recommends reviewing it to confirm the system is certified for your target contaminants. Ask any installer for the data sheet of the exact model they are quoting. Jorge can show you the documentation for the Living Water system he recommends after your free test.

Updated 2026-10-17 · Living Waters · Jorge Canela, Water Quality Specialist