How much plastic is in bottled water?
Emerging In 2024, researchers at Columbia and Rutgers universities used a new laser imaging method to count individual plastic particles down to about 100 nanometers in three popular US bottled water brands. They found between 110,000 and 370,000 particles per liter, an average of about 240,000. Around 90% were nanoplastics, which earlier methods could not count. That is 10 to 100 times more than previous estimates.
Surprisingly, the most common plastic was not PET, the bottle material, but polyamide (nylon), which is used in filters during bottling. Polystyrene, PVC and other industrial plastics were also found. So the problem is partly the bottle and partly the plastic equipment the water passes through. The bottled water industry has responded that there are no standard methods and no scientific consensus on health effects.
Bottles shed more when squeezed, reused, or left in a hot car or in the sun.
Is tap water better?
In most comparisons, yes. Tap water still contains microplastics, but typically far fewer than bottled water. A widely cited estimate suggests that someone who meets their water needs only with bottled water could take in an extra 90,000 particles a year, compared with about 4,000 for someone who drinks only tap water. Emerging Those figures predate nanoplastic counting, so both are likely underestimates.
In April 2026 the US EPA proposed listing microplastics as a priority contaminant group for drinking water for the first time. This starts a research process; there are no legal limits on microplastics in US tap water yet.
Water filters that remove microplastics
The key thing to check is certification, not marketing language. Phrases like "designed for microplastics" are not the same as a tested claim.
| Filter type | Typical pore size | Microplastics | Notes |
|---|---|---|---|
| Reverse osmosis (under-sink or countertop) | ~0.0001 µm | Removes nearly all, including much of the nano range | Look for NSF/ANSI 58 (RO) plus 401. Wastes some water; removes minerals. |
| Solid carbon block (pitcher, faucet, under-sink) | ~0.5–1 µm | Good for microplastics if certified | Only trust models listed under NSF/ANSI 401 for microplastics. |
| Ultrafiltration / hollow fiber | ~0.01–0.1 µm | Very good | Keeps minerals; check for third-party test data. |
| Loose granular carbon pitcher | Large gaps | Limited | Improves taste and chlorine; not reliable for particles. |
| Boiling + coffee filter | n/a | 25–90% in one lab study | Works best in hard water. Free, but slow. |
What NSF/ANSI 401 actually tests
NSF/ANSI 401 covers "emerging compounds". A filter with a microplastics claim under it must reduce test particles of 0.5 to 1 micrometer by at least 85%. A product can be certified to 401 for other contaminants without the microplastics claim, so check that the official listing names microplastics reduction for your exact cartridge model. Certification can also come from IAPMO or WQA, which test to the same standard.
See our product guide for what to look for in each filter type.
Does boiling water remove microplastics?
Emerging A 2024 study from Chinese researchers found that boiling tap water for five minutes caused calcium carbonate (limescale) to form and trap plastic particles. In hard water with about 300 mg of calcium carbonate per liter, up to 90% of added particles were removed. In soft water the figure was about 25%. Pouring the cooled water through a simple coffee filter caught the trapped particles.
Two cautions: the study added particles to water in the lab rather than measuring natural levels, and boiling in a plastic kettle may add particles back. Use a stainless steel or glass kettle.
Practical steps
- Drink tap water instead of bottled water where your tap water is safe to drink.
- If you want to filter, choose a model certified for microplastics reduction under NSF/ANSI 401, or a certified reverse osmosis system.
- Carry water in stainless steel or glass bottles.
- Never leave plastic water bottles in a hot car or direct sun, and do not refill single-use bottles repeatedly.
- Boil water in a steel or glass kettle, not a plastic one.
Frequently asked questions
Does a Brita filter remove microplastics?
It depends on the exact cartridge. Some pitcher cartridges are certified to NSF/ANSI 401 for microplastics reduction and many standard cartridges are not. Check the model number in the NSF certified products database rather than relying on packaging.
Does reverse osmosis remove microplastics?
Yes. Reverse osmosis membranes have pores far smaller than microplastics and remove nearly all of them, including much of the nanoplastic range. Choose a system certified to NSF/ANSI 58 for RO performance, and ideally 401 for a microplastics claim.
Is tap water free of microplastics?
No. Most tap water contains some microplastics, but studies generally find far fewer than in bottled water. Levels vary by source water, treatment plant and the pipes in your building.
Are reusable plastic water bottles a problem?
They shed less than single-use bottles when kept cool and handled gently, but wear, scratching, hot liquids and dishwasher heat increase shedding. Stainless steel or glass bottles avoid the issue.
Keep reading
Sources
- Qian et al. (2024), Rapid single-particle chemical imaging of nanoplastics by SRS microscopy, PNAS
- Yu et al. (2024), Drinking boiled tap water reduces human intake of nanoplastics and microplastics, Environmental Science & Technology Letters (via Yale e360)
- NSF certified drinking water treatment units database
- US EPA (April 2026): draft Contaminant Candidate List 6 adds microplastics
- Cox et al. (2019), Human Consumption of Microplastics, Environmental Science & Technology