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The spoon-sized problem we didn't notice
In February 2025, researchers at the University of New Mexico published a study in Nature Medicine with a finding that's hard to read calmly: the average human brain now contains roughly seven grams of microplastics — about the weight of a plastic spoon. They reached the number by analyzing brain tissue from autopsies in 2016 and 2024, and the comparison was the part that should keep us up at night. Plastic concentrations in human brains had increased by roughly 50% in just eight years.
That number didn't appear in isolation. Over the past three years, microplastics and nanoplastics have been documented in human placentas, testes, breast milk, semen, the meconium of newborns, the lining of arteries, and the lungs of people who never worked in plastics manufacturing. A landmark March 2024 paper in the New England Journal of Medicinetracked patients who had plaque removed from their carotid arteries: those whose plaque contained microplastics had a higher rate of heart attack, stroke, and death over the following two years than those whose plaque didn't.
We are, as one researcher put it in early 2025, "born pre-polluted." The question is no longer whether microplastics are in our bodies. The question is what's putting them there, and what — realistically — anyone can do about it.
A meaningful share of the answer points back to drinking water. And, more uncomfortably, to the plastic pitchers many of us bought specifically to make our water cleaner.
This is the story of how we got here, what the most current research actually says, and why we built Duryn the way we did — including the design decisions almost no other "glass" or "premium" water filter has made.
What microplastics actually are (and why size matters more than people think)
The term "microplastic" covers any plastic fragment between 5 millimeters and 1 micrometer in size. Below 1 micrometer, the same particle is called a nanoplastic — small enough that it's measured in billionths of a meter. For scale: a human hair is about 70 micrometers across. A standard Brita pitcher filter has a pore size of roughly 3 micrometers. Most nanoplastics are at least thirty times smaller than the holes in the filter many people are relying on.
Microplastics come from two main sources. Primary microplastics are manufactured small — the microbeads in older cosmetics formulas, the fibers shed from polyester clothing in a washing machine, the abraded particles from car tires on every road surface in the world. Secondary microplastics are what every other piece of plastic eventually becomes. UV light, heat, mechanical stress, and time break larger plastic objects into smaller ones, and there is no theoretical limit to how small they can get. Nature, in this specific case, does not break plastic down. It only breaks plastic up.
The reason size matters more than total volume becomes clear at the nanoscale. Once particles drop below about 100 nanometers, they're small enough to cross biological barriers that microplastics cannot — including the blood-brain barrier and the placental barrier. They can be absorbed across intestinal walls and enter the bloodstream directly, rather than passing through the gut. This is why the same researchers who used to count microplastics by the dozen are now counting nanoplastics by the hundred thousand, and why the health implications have suddenly gotten more urgent.
What's actually in your water — tap and bottled
The clearest data we have on water contamination is from a January 2024 study published in the Proceedings of the National Academy of Sciences by researchers at Columbia University and Rutgers. Using a new laser-based imaging technique called stimulated Raman scattering microscopy, the team analyzed three popular bottled water brands sold in the United States.
What they found upended the previous consensus. Earlier studies, working with older technology, had found around 325 plastic particles per liter of bottled water. The new method found an average of 240,000 plastic fragments per liter — between 10 and 100 times more than anyone had previously detected. About 90% of those particles were nanoplastics; only 10% were large enough to qualify as microplastics. The most common plastic types identified were PET (the polymer the bottle itself is made from) and polyamide — a nylon commonly used in the very filters bottlers use to "purify" the water before sealing it in.
That last detail is worth sitting with for a moment. Some of the plastic in bottled water appears to come from the equipment used to filter the water in the first place.
Tap water is not a clean alternative. A 2017 global study found microplastic contamination in 83% of tap water samples worldwide; in the United States, the figure was 94%. Levels were lower in Europe — around 72% in countries like the UK, Germany, and France — but still pervasive enough that "lower" doesn't mean "safe." A 2024 study found that boiling hard tap water can encapsulate some plastic particles in calcium carbonate precipitates, but the effect is unreliable and varies enormously with local water hardness.
The realistic takeaway is that virtually every drinking water source most people have access to contains some level of microplastic and nanoplastic contamination. The question is how much you let through to the glass — and, just as importantly, what you don't add along the way.
The pitcher paradox
Most people who care about clean water own a plastic filter pitcher. Brita, PUR, ZeroWater, Aquasana — variations on the same fundamental design: a plastic reservoir, a plastic filter housing, a plastic spout, sometimes a plastic lid. The water passes through a granular activated carbon cartridge that reduces chlorine and improves taste, then sits in a plastic vessel for hours or days before being poured into a glass.
In 2020, ConsumerLab — an independent product testing organization — ran one of the only direct comparison studies on what these pitchers actually do to microplastic levels. They started with tap water containing 33.5 microplastic particles per liter and ran it through four leading pitcher brands. The results were sharply uneven. One pitcher removed all detectable microplastics. Two reduced them by 80% and 36%, respectively.
The fourth pitcher increased the microplastic count to 437.4 particles per liter. That's a 1,206% increase over the unfiltered tap water. Even after additional flushes, the pitcher continued to add measurable plastic to the water passing through it.
ConsumerLab didn't single out a specific brand as the worst offender in their public summary, and the design specifics of which pitcher did what matter less than the underlying mechanism: a plastic pitcher with a plastic-housed filter sitting in a kitchen for weeks or months can shed particles into the water it's supposed to be cleaning. Independent water-filtration researchers have since confirmed that polypropylene — the plastic Brita and most major brands use for their reservoirs — can release microplastic fragments under conditions including UV exposure, mechanical stress, and biofilm growth. Those conditions are not exotic. They describe a normal kitchen.
There's a second layer to this problem that gets less attention. Even a Brita pitcher's filter cartridge housing is itself made of plastic, with the activated carbon and ion-exchange resin contained inside a plastic shell. Every cartridge change means new plastic entering the water flow path. This is true of nearly every "premium" filter pitcher on the market today, including ones that market themselves as glass. Aarke's glass pitcher, for example, has a glass body — but the cartridge that sits inside it has a plastic housing, and the cartridge itself contains ion-exchange resin beads, which are a polystyrene-based plastic that the water flows through and contacts continuously.
Brita's standard cartridge, which is what most pitchers in homes around the world use, is not certified for microplastic reduction. Brita does sell a separate Elite filter that carries an NSF/ANSI 401 certification for microplastic reduction, and that distinction matters — but it's worth noting that no major plastic-pitcher brand certifies its standard filter against the contaminant most consumers worry about most.
The irony of the situation is uncomfortable but real: many people are filtering their water specifically to reduce contaminants, and storing the result in a plastic vessel that may, under normal use, be adding a class of contaminant the filter wasn't designed to remove.
What "plastic-free" actually means in a water filter (and why most aren't)
Once you start looking, the marketing gets slippery. There are pitchers that call themselves "glass," and the body is glass — but the lid is plastic, the spout is plastic, and the cartridge housing is plastic. There are stainless steel countertop systems where the body is steel — but the cartridge inside is, again, plastic-housed. There are reverse osmosis systems that produce ultra-clean water — but route it through plastic tubing and store it in plastic bladders.
A genuinely plastic-free water filter, in the sense most consumers actually mean when they ask for one, would need to meet four conditions in the structural water-contact path:
- The vessel that holds the water has to be glass, ceramic, or stainless steel.
- The lid and any moving parts in contact with water have to be metal, wood, or ceramic.
- The faucet or spout has to be metal.
- The cartridge housing itself — the part the water flows through to be filtered — has to be made of something other than plastic.
That fourth condition is the hardest to meet, and it's where almost every "plastic-free" or "glass" pitcher on the market quietly compromises. Building a cartridge housing from stainless steel and ceramic instead of plastic is more expensive, harder to manufacture, harder to seal reliably, and slower to bring to market. The path of least resistance is to put a plastic cartridge inside a glass body and call the result plastic-free.
There's also a fifth question, which is more nuanced: what's inside the cartridge. Most premium filter cartridges contain ion-exchange resin beads — small spherical polymer particles, typically polystyrene crosslinked with divinylbenzene, which are technically plastic. The water flows through and contacts these beads continuously. Aarke uses ion-exchange resin. Brita uses ion-exchange resin. Most "lead reduction" or "heavy metal" filters rely on ion-exchange resin. It's the standard approach in the industry, and it's almost never disclosed plainly to consumers.
These two together — the cartridge housing and the filtration media — are where the real plastic exposure inside any filter system actually happens, and it's where almost every brand glosses over the details.
How (and why) we built Duryn
Duryn started from a simple question we kept asking ourselves and not getting a clean answer to: if microplastics are in our water, and the latest research keeps finding them in places we'd rather they not be, why is virtually every consumer water filter on the market still made of plastic?
We spent over a year on the engineering before we ever ran a marketing campaign. The decisions that took the longest were the ones almost no one would notice from a product photo, but they're the ones we think actually matter.
The body is borosilicate glass. Borosilicate is the same glass used in laboratory glassware and high-end cookware — it's thermally stable, it doesn't leach chemicals into water at any temperature water normally encounters, and it doesn't degrade under UV light the way plastic polymers do. It's heavier than plastic, more expensive to ship, and easier to break, and we accepted all of those trade-offs because the alternative was a plastic body sitting on a kitchen counter for years.
The internals are 304 stainless steel. The internal water-routing components — the parts most consumers never see and most brands don't talk about — are made from food-grade 304 stainless steel, the same grade used in commercial kitchen equipment and pharmaceutical processing. There's no internal plastic basin holding filtered water before it reaches the spout.
The lid is solid walnut. A small detail, but a real one. Most pitcher lids are plastic, often a textured polypropylene or ABS that contacts the water vapor in the headspace of the reservoir. Our lid is FSC-certified solid walnut, finished with food-safe oils. It looks like an heirloom kitchen object because it's built like one.
The cartridge housing itself is stainless steel and ceramic. This is the part we keep coming back to in conversations with people who've already done their research, because it's the part nearly every other "glass" or "plastic-free" pitcher gets wrong. The cartridge inside a Duryn pitcher is housed in a stainless steel shell with a ceramic filtration layer. Water flowing through the cartridge does not contact a plastic housing at any point. To our knowledge, this makes Duryn the only consumer water filter pitcher on the market with a fully plastic-free structural water-contact path.
And — the decision most water-filter brands don't make — the filter media inside is just coconut shell activated carbon. No ion-exchange resin. No polystyrene beads. No synthetic polymer membrane. Just a single coconut-shell-derived activated carbon block, manufactured from food-grade carbon sourced from coconut shells, which is one of the most chemically pure forms of activated carbon available.
We say "to our knowledge" deliberately on the structural claim. The water filtration market is large, and we can't claim we've audited every product in every region. But we've looked carefully, and we've yet to find another consumer pitcher where the housing, body, lid, faucet, and cartridge shell are all plastic-free and the filter media itself contains no ion-exchange resin or synthetic polymer membrane. If one exists, we'd like to know about it.
What carbon-only filtration does — and what it doesn't
We owe you the honest version of this section, because plenty of brands oversell what their filter can do.
A high-quality coconut shell activated carbon block reduces chlorine, chloramines, taste and odor compounds, many volatile organic compounds, certain pesticides, and a meaningful portion of the larger microplastic particles present in tap water through size-based filtration. Carbon block adsorption is one of the oldest, best-understood water filtration mechanisms in the world. It's the technology used in the filters that municipalities, hospitals, and the Berkey-style emergency systems all rely on. Done right, it's effective. Done poorly, it's a disappointment.
Here's what carbon-block filtration alone cannot reliably do, and we want to be straightforward about it: it does not capture nanoplastics. It does not certifiably reduce dissolved heavy metals like lead at the levels that ion-exchange resin can. And it does not achieve the same particle size threshold that ultrafiltration membranes can.
We made a deliberate choice to design around carbon block alone, rather than stack additional filtration layers, for two reasons. The first is design philosophy: every additional component in a water filter is another opportunity to introduce plastic into the water path. Ion-exchange resin is plastic. Synthetic UF membranes are plastic. Adding those technologies to chase additional contaminant claims would have meant compromising the core thing Duryn is for.
The second is honesty. We'd rather make a smaller number of claims and stand behind them than build a marketing story around a contaminant list that most consumers never read. If you live in a region with documented heavy metal problems in your tap water, a carbon-only pitcher of any brand is not the right product for you, and we'll tell you that. You need a system with certified lead reduction, and Duryn is not currently that system. What Duryn is built for is the much more common case: tap water that's broadly safe to drink, that contains microplastics and chlorine and the kind of background contamination almost everyone deals with, and that you'd prefer to reduce daily without introducing more plastic into the process.
The honest framing is this: Duryn reduces what a well-designed coconut carbon block can reduce, in a vessel that doesn't add plastic back to the water you've just filtered.
The Aarke comparison, specifically
Because we get asked about this often: Aarke makes a beautiful pitcher. The glass body is real glass, the visual design is genuinely premium, and we respect what they've built. But the comparison most consumers think they're making isn't quite the comparison that's actually on the table.
Aarke's cartridge housing is plastic. The filter media inside it is activated carbon plus ion-exchange resin — a polymer the water contacts continuously. The lid components include plastic. The pitcher is plastic-free in the body, but plastic-present in the parts most consumers don't see when they pick it up off a shelf.
Duryn was designed specifically to address the gaps Aarke and similar "glass" pitchers leave open: stainless steel and ceramic cartridge housing instead of plastic, carbon-only filter media instead of carbon plus ion-exchange resin, and a structural design where the parts most in contact with the water you'll actually drink are the parts most carefully engineered to be plastic-free.
We're not telling anyone that Aarke is a bad pitcher. We're telling you what's actually inside it, because almost no one else will.
What you can actually do today
If you've read this far, you might be looking for a clear next step. There are a few honest ones.
Stop drinking bottled water for routine use, especially water that's been sitting in heat or sunlight. The Columbia study put a number on something most environmental researchers had suspected for years. Bottled water is, on average, the most plastic-saturated water source most people drink. If you live in a country with reliable municipal tap water — most of Western Europe, most of North America, most of urban East Asia — you are almost certainly drinking less plastic from your tap than from a single-use plastic bottle. This is true even before any filtration.
If you use a plastic filter pitcher, be aware of what it can and cannot do. Standard granular activated carbon cartridges, including the ones in entry-level Brita pitchers, are not designed to remove microplastics and don't claim to. Brita's Elite cartridge is certified to NSF/ANSI 401 for microplastic reduction, and that's a meaningful upgrade if you're committed to staying with the brand. Replace cartridges on schedule. Keep the pitcher out of direct sunlight and away from heat sources. Don't run pitcher components through a dishwasher — heat and detergent both accelerate plastic degradation.
If you're going to invest in a pitcher anyway, the case for one without plastic in the water path is stronger than it was even two years ago. The research base on microplastic health effects is moving fast, and the trend line in every recent study has been: more particles found, smaller particles found, more places in the body where they accumulate. This is one of the relatively few consumer health questions where the science is moving in a direction that suggests caution rather than reassurance.
Drink the water once it's filtered. Filtered water sitting in a vessel for days, regardless of what the vessel is made of, is filtered water that's had more time to interact with whatever contains it. A pitcher you refill every day or two is doing more for you than a pitcher that sits in the fridge for a week.
A measured note on what we know and don't know
We've tried to write this in a way that respects the actual state of the science. Some things are clear: microplastics are in human bodies, they're getting smaller and more numerous over time, and they appear to be associated with health risks the medical research community is taking seriously. Some things are not yet clear: exactly how much exposure produces measurable harm, which specific exposure routes matter most, and which interventions produce the largest reductions in body burden.
What is also clear, though, is that the major sources of plastic exposure in most people's daily lives are knowable, and water is one of them. Reducing plastic in your water is one of the few interventions where the cost-benefit math is straightforward: it's a one-time purchase, it lasts years, and it removes a contamination route every single day for the life of the product.
We built Duryn for people who'd already done the research and couldn't find a product that matched the conclusions they'd reached. If that's where you are, you'll know whether this is the right pitcher for you. If you're newer to the topic, the honest version of the advice is: do the reading, decide what you're comfortable with, and don't let the perfect become the enemy of the better. Any reduction in plastic exposure beats no reduction. A glass-bodied pitcher with a plastic cartridge is still meaningfully better than a fully plastic pitcher. A pitcher with a fully plastic-free water-contact path and a simple, single-stage carbon block is meaningfully better still. The right choice is the one you'll actually use, every day, for years.
Sources and further reading
- Nihart, A. J., et al. Bioaccumulation of microplastics in decedent human brains. Nature Medicine, February 2025.
- Marfella, R., et al. Microplastics and nanoplastics in atheromas and cardiovascular events. New England Journal of Medicine, March 2024.
- Qian, N., et al. Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proceedings of the National Academy of Sciences, January 2024.
- ConsumerLab. Water Filter Pitchers Review: Tests of Aquasana, Brita, PUR, ZeroWater. October 2020.
- Hu, C., et al. Microplastic presence in dog and human testis and its potential association with sperm count.Toxicological Sciences, 2024.
- Garcia, M. A., et al. Quantitation and identification of microplastics accumulation in human placental specimens.Toxicological Sciences, 2024.
- Kosuth, M., et al. Anthropogenic contamination of tap water, beer, and sea salt. PLoS ONE, 2018.
Duryn is a borosilicate glass and stainless steel water filter pitcher with a ceramic and stainless steel cartridge housing, and a single-stage coconut shell activated carbon block as filter media. To our knowledge, it is the only consumer water filter pitcher with both a fully plastic-free structural water-contact path and filter media free of ion-exchange resin or synthetic polymer membranes. [Learn more about how it's built →]