iSpring RCC7AK
Almost everyone, because the certification actually covers what people buy RO to remove
- Owner rating
- 4.6 from 15,106 ratings
- Certification
- NSF/ANSI 58, NSF/ANSI 372, for 9 named contaminants
Water filtration, tested, scored and explained
Every recommendation here is scored on a published formula, and every certification is verified in the certifying body's own records rather than taken from the listing that claims it.
- 441
- systems classified in our certification survey
- 100%
- of certifications looked up in the certifier’s own database
- 0
- placements a brand can buy
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What we would buy, by where the filter goes
One product from each of the categories we cover, taken from the top of each page in the order they appear here. The score is the published formula and the certification line is what that product's certificate actually covers, which is rarely what the box says.
iSpring WGB32B-PB
Older homes, or anywhere a water test has shown lead
- Owner rating
- 4.8 from 178 ratings
- Certification
- Third-party tested, per manufacturer
iSpring WGB32B-KDS+WSP50
Wells with grit, scale or a sulphur smell rather than rust staining
- Owner rating
- 4.7 from 2,224 ratings
- Certification
- Third-party tested, per manufacturer
Brondell H2O+
Anyone whose worry is a named contaminant rather than taste, who can plumb a filter in
- Owner rating
- 4.6 from 1,236 ratings
- Certification
- NSF/ANSI 42, NSF/ANSI 53, NSF/ANSI 401, CSA B483.1, for 13 named contaminants
Brondell H630
Most kitchens on municipal water, and the one with a certification you can look up
- Owner rating
- 4.2 from 455 ratings
- Certification
- NSF/ANSI 42, NSF/ANSI 53, NSF/ANSI 401, for 22 named contaminants
Brondell VivaSpring Compact Shower Filter
Anyone who likes their shower head and wants a filter with a standard behind it
- Owner rating
- 4.4 from 670 ratings
- Certification
- Third-party tested, per manufacturer
Every category we have scored
Under sink Best under-sink reverse osmosis systems Every certification checked against the certifier’s own database, not the listing. 4 systems scored Whole house Best whole house water filter systems Scored and ranked, with the right pick for city water and for wells. 5 systems scored Well water Best well water filtration systems Treated in an order, not solved by one product, plus the UV class that decides whether a lamp is rated for a well. 2 systems scored Microplastics Best water filters for microplastics A certifiable claim, and the sixteen claims inside NSF/ANSI 401 are granted one test at a time. 4 filters scored Countertop Best countertop water filters Two categories in one, and buying the expensive half for a taste problem is the common mistake. 4 filters scored Shower Best shower filters Chlorine devices, and one of them names the standard written for the category. 2 filters scored Faucet Best faucet water filters The cheapest fix for chlorine taste, and the running cost that catches people out. 4 filters compared Travel Best portable water filters Hollow fibre membranes rated in microns, for hiking, travel and the power cut. 4 filters compared
Already own the system
A certification is granted to a system in one configuration, and the certificate names the cartridge that configuration includes. These pages print those part numbers.
Every replacement filter Start here if you know the system and need the cartridge. Refrigerator cartridges The same filter is sold certified for taste and certified for lead. The codes that tell them apart. Reverse osmosis cartridges Your certificate names the cartridge it was granted with. Here are the codes. Whole house cartridges Sediment, carbon and iron stages, and which of them your housing takes.
How the market actually works
Nothing in this section sells anything. These are the pages that explain the mechanisms, the standards and what we found when we measured them.
Original research Most water filters are not certified for what they remove We classified 441 systems. Half invoke NSF. One in seven says which standard. Guide How do water filters work? The six mechanisms, what each removes, and what each one misses. Guide Do water filters remove fluoride? Carbon removes almost none. Four methods do work, and here is the full comparison. Guide Does a Brita filter remove lead? One of their two filters is certified for it. Both are sold as certified. Guide Chlorine and chloramine are not the same claim 5,553 certified models hold one. 216 hold the other. Most utilities are moving to the second. Guide What does filtered water actually mean? The FDA defines six kinds of bottled water by name. "Filtered" is not one of them.
Why trust this site
A formula, not a hunch
Every score is calculated from owner ratings, certification, filter cartridges and warranty, each measured against what is achievable in that category. The weights and benchmarks are published.
See the formula →Our own research
We classified the certification language on 441 water filtration systems, and published the script that rebuilds the survey from scratch. Nobody else has measured this.
Read the findings →Checked at the source
Every certification is looked up in the certifying body's own database by model number, and the card names it and links it. A manufacturer claim we cannot trace to a source is scored as a claim, not as a fact.
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