Microplastics in Drinking Water: What Actually Filters Them Out (and What Doesn't)
City Water Quality Guide
Microplastics in Drinking Water: What Actually Filters Them Out (and What Doesn't)
The short answer: reverse osmosis is the only residential filter that reliably removes both microplastics and the far smaller nanoplastics, and a good under-sink RO system costs $275, not thousands. After 32 years in water treatment, I've watched plenty of scary headlines come and go. This one is real but manageable, and the honest solution is cheaper than most people expect. This guide covers what the studies actually found (including why bottled water is worse than tap), which filters work at which particle sizes, and which popular products don't do what people assume they do.
The Short Version
- Microplastics are in most tap water and nearly all bottled water. A January 2024 Columbia/Rutgers study found roughly 240,000 plastic particles per liter of bottled water, about 90% of them nanoplastics. Tap water contains far fewer particles than bottled. Switching to bottled water is the one move that makes the problem worse.
- Best removal: under-sink reverse osmosis. An RO membrane rejects particles down to about 0.0001 microns, small enough to catch nanoplastics. The MAW-50 under-sink RO ($275) or the quick-change Pure-75 ($595) handles drinking and cooking water at one tap.
- Good: certified carbon block filters. Solid carbon block cartridges rated at 0.5 microns catch most microplastics but not nanoplastics. Look for an NSF/ANSI 401 microplastics reduction claim.
- Partial: whole house systems. A whole house water filtration system with tight sediment filtration catches larger fragments and fixes the chlorine, taste, and chemical problems city water actually has, but it is not a microplastics barrier on its own. Pair it with under-sink RO for drinking water.
- Not reliable: pitcher filters, fridge filters, and standard sediment filters. Some certified pitchers do reduce microplastics; most don't carry the certification. A 5-micron sediment cartridge alone misses almost everything the studies measured.
- Can't test for them at home, but you can test for the 47 city water contaminants that matter more. The City Water Test Kit ($199) uses a certified lab, and the free city water report lookup on our whole house collection page shows what your utility has already found.
What's the Right Microplastics Setup for Your Home?
Two quick questions. Honest answer at the end, even if it's the $275 option.
What This Article Covers
- What Microplastics and Nanoplastics Actually Are
- What the Studies Found (Bottled vs Tap)
- The Size Problem: Why Microns Decide Everything
- What Actually Removes Microplastics
- What Doesn't Work (or Only Sort Of)
- My Honest Recommendation
- Can You Test Your Water for Microplastics?
- Frequently Asked Questions
What Microplastics and Nanoplastics Actually Are
Microplastics are plastic fragments between 1 micron and 5 millimeters across. They come from packaging breaking down, synthetic clothing fibers shedding in the wash, tire dust, paint, and the slow weathering of every piece of plastic ever left outdoors. Nanoplastics are the next stage of that breakdown: particles smaller than 1 micron, which is where things get more concerning, because particles that small can pass through the gut lining and have been detected in human blood and tissue.
For scale: a human hair is about 70 microns thick. The particles that dominate drinking water are far smaller than anything you can see.
5 mm and up
~70 microns
1 to 5,000 microns
under 1 micron
~0.0001 microns
One thing I want to say up front, because this topic attracts a lot of fear-selling: the World Health Organization reviewed the evidence in its 2019 report on microplastics in drinking water and concluded that, based on the limited data available, microplastics in drinking water do not appear to pose a health risk at current levels. It also said we urgently need better research, especially on nanoplastics. That's the honest state of the science. Nobody should be panic-buying equipment over this. But reducing a poorly understood exposure with a $275 filter that also improves your water in a dozen other measurable ways is a reasonable, level-headed decision, and that's the spirit of this guide.
What the Studies Found (Bottled vs Tap)
Three studies define what we actually know about microplastics in drinking water. Here's what each one measured, with dates, because numbers without sources are just marketing.
| Study | What It Tested | What It Found |
|---|---|---|
| Orb Media / SUNY Fredonia (2017) | 159 tap water samples across 14 countries | 83% contained plastic particles, almost all fibers, with an overall average of about 4.3 particles per liter. North American samples had the highest densities. |
| Mason et al., Frontiers in Chemistry (2018), commissioned by Orb Media | 259 bottles from 11 major bottled water brands in 9 countries | 93% showed microplastic contamination, averaging about 325 particles per liter when smaller particles were included. Roughly double the contamination found in the same team's tap water study, with evidence pointing to the packaging and bottling process itself. |
| Qian et al., PNAS (January 2024), Columbia and Rutgers | Three popular US bottled water brands, using a new laser imaging method that can see nanoplastics for the first time | 110,000 to 370,000 particles per liter, averaging about 240,000. Roughly 90% were nanoplastics, 10 to 100 times more particles than earlier studies could detect. |
The pattern across all three is the finding most people miss: bottled water is consistently worse than tap water for microplastics. The bottle, the cap, and the bottling line shed plastic into the product. The 2024 study is summarized well by the National Institutes of Health, and the full WHO 2019 assessment is worth reading if you want the unfiltered science.
The Bottled Water Trap
I hear this on the phone regularly. A caller from upstate New York told me he'd been buying bottled water for thirty years because he didn't trust his tap or his aging filter. He was spending well over $1,000 a year to drink water that, according to every study on this page, contains more plastic than what comes out of his faucet. If microplastics are your concern, bottled water is not the escape hatch. Filtering your own tap water is cheaper and measurably cleaner.
The Size Problem: Why Microns Decide Everything
Every filter has a pore size, measured in microns. A filter removes particles larger than its rating and passes particles smaller than it. That single number tells you most of what you need to know about microplastics performance, because the particles in your water span five orders of magnitude in size.
| Filter Type | Typical Rating | Catches Microplastics? | Catches Nanoplastics? |
|---|---|---|---|
| Standard whole house sediment cartridge | 5 microns nominal | Only fragments larger than 5 microns; most measured particles pass through | No |
| Solid carbon block (quality under-sink or countertop) | 0.5 to 1 micron nominal | Yes, the large majority | Mostly no |
| Ultrafiltration membrane | ~0.01 to 0.02 microns | Yes | Most, but not the smallest |
| Reverse osmosis membrane | ~0.0001 microns | Yes | Yes |
Here's the context that makes this table matter: in the 2024 PNAS study, about 90% of the particles found were nanoplastics, smaller than 1 micron. That means a filter rated at 1 micron, which sounds impressively tight, still passes the vast majority of particles by count. Only RO gets meaningfully below the nanoplastic range. If you want the full breakdown of what an RO membrane rejects beyond plastics, read What Does Reverse Osmosis Remove?
What Actually Removes Microplastics
Under-Sink Reverse Osmosis
RO forces water through a semi-permeable membrane with pores around 0.0001 microns. That's roughly 10,000 times smaller than the nanoplastic threshold, and it's why RO is the one residential technology that addresses the 90% of particles the other filters miss. It also removes dissolved contaminants that no particle filter touches: lead, arsenic, nitrates, fluoride, sodium, and most PFAS.
Two systems I sell and stand behind:
- MAW-50 ($275 for the 4-stage, $325 for the 5-stage): tank-based, 50 gallons per day, the value pick for 1 to 3 people. Installs under the kitchen sink in an afternoon.
- Pure-75 ($595): 75 gallons per day with quarter-turn quick-change cartridges. Filter changes take about five minutes with no tools, which matters more than people think, because the filter you actually change on schedule beats the one you keep postponing.
For a deeper comparison of models and stages, see our best reverse osmosis system guide.
Certified Carbon Block Filters
A solid carbon block cartridge rated at 0.5 microns physically strains out most microplastic particles while also adsorbing chlorine and improving taste. The certification to look for is NSF/ANSI 401 with a microplastics reduction claim: it requires at least 85% reduction of test particles in the 0.5 to 1 micron range. That standard was written for microplastics, not nanoplastics, so treat carbon block as a solid partial answer. Many under-sink systems use carbon blocks as pre-filters ahead of an RO membrane, which is the best of both. Our under-sink filter guide covers when a carbon-only system makes sense.
Not sure whether carbon or RO fits your situation? The honest comparison is here: Carbon Filter vs Reverse Osmosis.
Whole House Carbon + Tight Sediment Filtration
I'll be straight about this because plenty of companies aren't: no whole house system reliably removes nanoplastics at the 7+ gallons per minute a household needs. Membranes tight enough to catch them would crush your water pressure. A whole house carbon filter like our Clack 2.5 cubic foot catalytic carbon system ($1,695) paired with a fine sediment pre-filter will catch larger plastic fragments and fibers, and more importantly it removes the chlorine, chloramine, disinfection byproducts, and taste problems that city water measurably has.
If a salesperson tries to sell you a whole house system as a microplastics solution, that's your cue to find another salesperson. Buy whole house filtration for what it actually does, and put a $275 RO at the kitchen sink for the plastics. The full treatment picture for municipal water is in our City Water Treatment Guide.
What Doesn't Work (or Only Sort Of)
Pitcher and Fridge Filters: Check the Certification, Not the Marketing
Pitcher filters vary enormously. A handful of premium pitchers and countertop gravity units are genuinely certified to NSF/ANSI 401 for microplastics reduction, and those do what they claim for particles down to about 0.5 microns. Most ordinary pitchers and refrigerator filters are loose granular carbon designed for taste and chlorine, with no meaningful particle rating at all. If the packaging doesn't say NSF/ANSI 401 microplastics reduction (or at minimum NSF/ANSI 42 particulate Class I), assume it doesn't remove them. Our countertop and pitcher filter guide covers which formats earn their place.
Standard Sediment Filters Alone
A typical 5-micron whole house sediment cartridge protects your plumbing and appliances from grit, and I recommend one ahead of nearly every system I sell. But against microplastics it only catches the largest fragments. The particles that dominate by count are 10 to 1,000 times smaller than its pores.
Boiling
Boiling kills bacteria and viruses. It does nothing to remove plastic particles, and boiling water in contact with plastic kettles or containers can increase them. Don't boil for this.
What a Real Customer Did
This layered approach (whole house for the house, RO for the glass) is exactly what experienced customers land on. Stuart Soled, a verified buyer, wrote in his review of his whole house setup: "The neutralizer is excellent quality, the control valve works flawlessly... I also put a small reverse osmosis under the sink just to make sure that the drinking water is perfect." That's the right instinct. Each stage does the job it's physically capable of, and the drinking water gets the finest barrier.
My Honest Recommendation
I sell $1,695 whole house systems. For this specific problem, most homes don't need one. Here's the honest hierarchy:
- Stop drinking bottled water. Free, and by every study on this page it's the single largest microplastics reduction available to you.
- Put reverse osmosis at the kitchen sink. The MAW-50 ($275) covers drinking, cooking, coffee, and pets for a small household; the Pure-75 ($595) for bigger families. This is where more than 95% of your ingestion exposure lives.
- Add whole house filtration for the reasons whole house filtration exists: chlorine and chloramine removal, disinfection byproducts, taste and odor at every tap, shower water quality. Microplastics ride along as a partial bonus, not the headline.
Notice the order. The cheapest item on the list does the most work against this particular contaminant. If someone's pitch runs the other direction, they're selling to your fear, not your water.
Can You Test Your Water for Microplastics?
Honest answer: not practically. Counting micro and nanoplastics requires laboratory imaging (the 2024 Columbia study used a purpose-built laser microscopy platform), and residential water labs don't offer it as a routine test. Anyone selling a home microplastics test strip is selling you a prop.
What you can do is find out what else is in your city water, which matters more for your actual buying decision. Two steps I recommend before spending anything on equipment:
- Look up your utility's existing data free. The city water report lookup on our whole house water filtration collection page pulls your utility's violation and contaminant records by ZIP code.
- Test at your own tap. The utility tests at the plant; your water then travels through miles of mains and your own plumbing. The City Water Test Kit ($199) is a certified independent lab analysis of 47 contaminants including lead, PFAS, disinfection byproducts, and metals. Our guide on how to test your tap water explains the whole process.
Send the results to Aidan and he'll tell you what, if anything, your water needs. Sometimes the answer is "your water is fine, just add the RO if the plastics bother you." You'll get that answer when it's true.
Frequently Asked Questions
Can any water filter remove microplastics?
Yes, but effectiveness depends entirely on pore size. Reverse osmosis (about 0.0001 microns) removes both microplastics and nanoplastics. Solid carbon block filters rated at 0.5 microns remove most microplastics but pass nanoplastics. Standard sediment filters, loose granular carbon pitchers, and refrigerator filters are not reliable for microplastics unless specifically certified under NSF/ANSI 401.
Do Brita and other pitcher filters remove microplastics?
Most standard pitcher filters use loose granular activated carbon designed for chlorine taste and odor, not fine particle removal, so they are not a reliable microplastics barrier. A small number of premium pitchers and gravity filters carry an NSF/ANSI 401 microplastics reduction certification, which requires at least 85% reduction of particles in the 0.5 to 1 micron range. Check for that specific certification rather than trusting front-of-box marketing.
Does boiling water remove microplastics?
No. Boiling kills microorganisms but does not remove plastic particles, and boiling water in plastic kettles or pouring it into plastic containers can add particles. Physical filtration is the only way to remove them, and reverse osmosis is the most complete option.
Does reverse osmosis remove nanoplastics?
Yes. An RO membrane rejects particles down to roughly 0.0001 microns, far below the 1 micron threshold that defines nanoplastics. That makes reverse osmosis the only common residential technology that addresses the roughly 90% of particles that the January 2024 Columbia/Rutgers PNAS study found were nano-sized. An under-sink RO system like the MAW-50 ($275) covers drinking and cooking water, which is where ingestion exposure happens.
Do whole house filters remove microplastics?
Partially. A whole house carbon system with a fine sediment pre-filter catches larger plastic fragments and fibers, but no whole house system reliably removes nanoplastics at household flow rates, because a membrane that tight would collapse your water pressure. Buy whole house filtration for chlorine, chloramine, disinfection byproducts, and whole-home taste, then add under-sink reverse osmosis for drinking water.
Does bottled water have more microplastics than tap water?
Yes, consistently. The 2018 Mason study found bottled water averaged about 325 particles per liter, roughly double what the same team measured in tap water in 2017. The January 2024 PNAS study, which could see nanoplastics for the first time, found an average of about 240,000 particles per liter in bottled water. The packaging and bottling process itself appears to be a major source. Filtering your own tap water is both cheaper and cleaner.
Can I test my water for microplastics at home?
No. Detecting and counting microplastics requires laboratory imaging techniques, and residential labs do not offer it as a routine test. What you can do is test your tap water for the 47 regulated and unregulated contaminants that drive real treatment decisions, using a certified lab kit like the City Water Test Kit ($199), and check your utility's public water quality data for free.
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About the Author: Aidan has been in the water treatment industry for 32 years, including 28 years of hands-on installations and service. Mid Atlantic Water is a wholesale distributor that ships commercial-grade water treatment systems directly to homeowners, cutting out the dealer markup and commissioned salespeople. Every recommendation in this article is based on field results and published research, not affiliate commissions, which is why the top recommendation on this page is a $275 system and not a $3,000 one.
Not sure what your water needs? Call or text Aidan at 800-460-5810 · Email support@midatlanticwater.net