Outside the kitchen cupboard
NSF/ANSI 401 certifies microplastic reduction using a test for particles 0.5 to 1 micron. The same standard defines a microplastic as 1 micron and up. Five filters, read from their own documentation and scored on what they are made of.
There are two things worth knowing before you spend anything on a filter to remove microplastics, and neither appears on a single product page we read.
The first is that the certification exists but does not test what you think it tests. The second is that most of these products are not certified for microplastics at all — they are tested, which is a different word doing a lot of quiet work.
We do not test filters and we have no laboratory. Everything below is read from each manufacturer's own site and quoted. The score is our usual materials score, out of 100, read for a filter: what the water sits in and passes through is worth 60, the lids, seals and housings 25, and whether anyone outside the company has confirmed it 15. The full rubric is here.
NSF/ANSI 401 is the standard that covers microplastic reduction, and it is real. A filter certified to it has genuinely passed something. But look at what.
Writing in Water Conditioning & Purification in January 2022, Rick Andrew — who runs NSF’s own global water programme, so this is an insider explanation rather than a criticism — sets out how the claim was built. The standard defines microplastics as “particles of plastic having a size in the range of 1 µm to 5,000 µm”. The test, borrowed from NSF/ANSI 42’s particulate method, requires a system to “reduce the number of particles in the size range of ≥ 0.5 µm to < 1 µm by 85 percent”.
Read those two sentences together. The certified size band sits entirely below the bottom of the standard’s own definition. Not one particle that meets the definition of a microplastic is measured by the test that certifies microplastic reduction.
There is a sensible engineering reason for this, and it deserves saying: a filter that removes 85% of sub-micron particles will almost certainly remove larger ones too, and sub-micron particles are the harder test. It is a surrogate, chosen deliberately, and a defensible one. What is not defensible is that you cannot find any of this on a product page, or on NSF’s own consumer FAQ, which tells shoppers only that filters “certified to NSF/ANSI 401 helps to reduce these contaminants”.
So: a 401 certification is meaningful evidence that a filter removes very small particles. It is not a measurement of microplastic removal as the standard itself defines a microplastic. Both of those are true at once, and every article we found telling you to “look for NSF 401” stops before the second one.
This is the distinction that decides most of the scores below, and once you have seen it you cannot unsee it on a product page.
Certified means a third party audits the product, the factory and the ongoing production, and lists it publicly so you can look it up. Tested means somebody ran a sample once and the company is telling you about the result.
Three of the five products here — Epic, Clearly Filtered and, for its current element, Berkey — are certified only to NSF/ANSI 42 (chlorine, taste and odour) and 372 (lead-free materials). Those are the two least demanding standards in the family. Every health claim they make — 53 for lead and cysts, 401 for microplastics and pharmaceuticals, P231 for bacteria — sits under “independently tested to”.
Epic states the split openly on its own site, which we want to credit: “NSF Certified to NSF/ANSI Standard 42 and NSF/ANSI/CAN 372” and separately “Independently tested to NSF/ANSI Standards 42, 53, 401, and P231”. Clearly Filtered goes further and names the laboratory — IAPMO New Jersey, ISO 17025 accredited — which almost nobody does.
The outlier is ZeroWater, and not in the direction you would expect from the marketing. It is genuinely certified by IAPMO R&T to NSF/ANSI 53, naming the contaminants and a 15-gallon capacity. It also makes no quantified microplastics claim at all — its own page says only that activated carbon “has shown good results at capturing these tiny particles”. The brand with the strongest certification makes the weakest claim. That happens more often than you would think, and it is usually the tell.
Worth sitting with. You are buying a device to take plastic particles out of your water, and in four of the five cases the water then sits in a plastic jug, having passed through a plastic housing.
We are not claiming the jug sheds into your water — nobody has measured that, and we are not going to invent it. The point is narrower and about materials, which is what this site scores: LifeStraw’s glass pitcher is the only one in this group where the water sits in something inert, and it is why it is the only one to clear 60.
Two of the makers name their plastics properly, which counts for something. ZeroWater states “BPA Free Polypropylene and ABS”. Epic states “Polypropylene and Tritan”. Clearly Filtered names Tritan, though only in a support article rather than on the product page. Nobody publishes a resin grade.
| Product | Materials score | What it is made of | What is actually certified |
|---|---|---|---|
| LifeStraw Home 7-Cup Glass$64.95 | 77/100 | Borosilicate glass pitcher · silicone base · polysulfone membrane · plastic filter housing | WQA-certified to NSF/ANSI 42, 53 and 401, plus P473 and EPA/NSF P231 |
| Travel Berkey 1.5 gal$344 | 55/100 | AISI 304 stainless steel chamber, lid, knob and screw · Black Berkey element composition never disclosed | None. The elements are “tested by accredited third-party labs that have reported that the elements meet ANSI/NSF (Std. 53) protocol” — labs unnamed |
| ZeroWater 10-Cup$37.99 | 50/100 | “BPA Free Polypropylene and ABS” pitcher · coal-based activated carbon, KDF and ion exchange resin · polypropylene filter housing | IAPMO R&T certified to NSF/ANSI 42 and 53, naming the contaminants and a 15-gallon capacity |
| Clearly Filtered Pitcher$99 | 46/100 | “Medical-grade” Tritan pitcher · “Affinity®” media, six materials, none named · housing given only as “medical-grade plastic” | NSF-certified to 42 and 372 only. Everything else is lab testing — but they name the lab, IAPMO New Jersey, ISO 17025 |
| Epic Pure XP Pitcherfrom $84 | 45/100 | “Polypropylene and Tritan” pitcher · nanofiber media over a carbon fibre block · polypropylene housing | NSF-certified to 42 and 372 only. 53, 401 and P231 are “independently tested to”, labs unnamed |
Lid material and country of manufacture not published. The filter housing is described only as “durable plastic materials that should not break down”.
The best vessel material here and the worst filter disclosure. Also under an EPA stop-sale order — see below.
The most honest certification in the set and the least ambitious marketing claim. Those two facts are related.
Names its laboratory, which most do not, and refuses to name a single one of the six materials doing the filtering.
States the certified/tested split openly on its own page, which is to its credit. Filter life is given as both 100 and 150 gallons in different places.
Berkey is the one product here with a genuinely excellent vessel — AISI 304 stainless steel, stated plainly, with the chambers “assembled in the USA from US and imported parts”. On materials alone that beats every plastic pitcher in the set, and the score reflects it.
Three things sit alongside that. First, the composition of the Black Berkey element — the part doing the filtering — is never disclosed anywhere on the manufacturer’s site. Second, that element is not certified: the wording is that accredited labs “have reported that the elements meet ANSI/NSF (Std. 53) protocol”, and the labs are not named. Meeting a protocol, per unnamed labs, is about as far from a listed certification as a sentence can get while still sounding like one.
Third, in 2023 the US EPA issued a Stop Sale, Use, or Removal Order against Berkey International LLC under FIFRA, covering the Black Berkey filter products, on the grounds that they were unregistered and misbranded pesticides. The manufacturer sued; the case was dismissed for lack of standing in November 2023 and an injunction to lift the order was denied in January 2024. As of writing, Black Berkey elements show as unavailable on the maker’s own store, and it now sells a Phoenix Gravity element in their place.
The Phoenix element is, notably, better documented than the one it replaces: certified to NSF/ANSI 42 and 372, housing given as “super durable glass-filled polymer which is BPA free and NSF/FDA food contact compliant”, media given as “premium CTC 60 coconut shell carbon”. One brand, two elements, opposite disclosure.
New scores, brands that finally answered, and any rule change that affects what you can buy. The list is not open yet — email us and we will add you when it is.