Water first passes through a hollow fiber membrane filter-a tangle of thin polymer tubes with 0.2-micron pores in their walls. The LifeStraw filter consists of two filter elements. We experienced some slowing of filtration over the Pur Lead Reduction filter’s 40-gallon lifespan, but not outright clogging. But in our testing, the Longlast+ frequently clogged well before then, and numerous owners report the same problem. Brita’s competitor, the Longlast+, is certified for more contaminants (30) and is also rated to last three times longer (120 gallons versus 40). It’s also certified for four “aesthetic” ANSI/NSF Standard 42 contaminants that affect water taste (especially chlorine) 10 ANSI/NSF Standard 53 contaminants (encompassing organic compounds including pesticides, and heavy metals including mercury and cadmium), and eight ANSI/NSF Standard 401 “emerging contaminants,” which are increasingly found in US water supplies (including bisphenol A and estrone, a form of the human hormone estrogen). Pur’s Replacement Filter with Lead Reduction (model number PPF951K) is ANSI/NSF–certified for 23 contaminants, including (obviously) lead. The heart of any water-filter system is the filter itself, so let’s start there. Reputation and reviews: We weighed the trends we found in filter owner reviews-both positive and negative-to get a fuller picture of how they perform, beyond their certification statistics and our own experience.Wide availability: We especially wanted our recommended replacement filters to be easy to find for the foreseeable future.So the cost per filter and the replacement schedule give a sense of long-term cost competitiveness. Cost competitiveness: Filters have to be replaced regularly, usually every two months/40 gallons, though there are exceptions.(That is, the fact that a filter is certified under a given ANSI/NSF standard-42, 53, 401-doesn’t tell you specifically which contaminants it’s actually certified for.) Certification is done on a strict pass/fail basis there are no certifications for “pretty good” or “close enough.” There are many potential water contaminants, and filters must be tested and certified for each one.
Total ANSI/NSF certification: More is better.Our reporting has shown that some of this testing isn’t as reliable as we’d like, so we are very careful when evaluating such claims. Misleading claims: Unfortunately, many filter makers use phrases like “independently tested to ANSI/NSF standards” to imply that they’re certified.But if clogging is an issue or a concern with your water filtering, those minor shortcomings pale in comparison. A few design and filtration-speed quibbles, which are outlined in the main discussion below, reflect why it’s not our top pick or runner-up. The fact that LifeStraw makes these test results public and has years of experience in supplying filtration for disaster relief, developing-world water-quality initiatives, and outdoors enthusiasts, means we trust its claims. The LifeStraw also has four ANSI/NSF certifications (for chlorine, taste and odor, lead, and mercury), and it’s been independently tested by certified labs against dozens of other ANSI/NSF standards. For anyone who has experienced clogging with another water filter-including our recommended Purs and Britas-or who is looking for a solution to known rusty or otherwise sediment-rich tap water, it’s our clear pick. We ran 2.5 gallons of heavily rust-contaminated water through the LifeStraw Home Dispenser, and although it slowed slightly, it never stopped filtering.
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