EPA legal limit
No federal limit
Maximum Contaminant Level
EWG health guideline
No guideline
Science-based, stricter target
Health effects
Microplastics are confirmed present in human tissue — including blood, lung, liver, kidney, and placenta. Animal studies at high concentrations show inflammation, oxidative stress, and gut microbiome disruption. A 2024 New England Journal of Medicine study found that patients with microplastics and nanoplastics in atherosclerotic plaques had significantly higher rates of heart attack, stroke, and death than those without — though causation was not established. No dose-response threshold for human health effects from drinking water exposure has been identified. The WHO (2019) concluded that at current levels microplastics "do not appear to pose a risk" while calling for more research.
Where it comes from
Microplastics enter water supplies from multiple routes: breakdown of larger plastic items in the environment (bottles, packaging, agricultural films), synthetic textile fibres shed in laundry, plastic pipe degradation in distribution systems, and treated wastewater discharge. Bottled water typically contains higher concentrations of microplastics than filtered tap water — plastic bottles and caps shed particles into the water. UCMR5 does not include microplastics — no systematic federal monitoring data exists at the utility level.
How it's regulated
Not regulated. No EPA MCL for microplastics exists as of May 2026. California adopted a monitoring framework in 2022 — the first in the world — but no enforceable limits have been set. EPA's Contaminant Candidate List 5 (CCL5) includes microplastics under consideration. Because microplastics are not in SDWIS or UCMR5, WaterHealthCheck cannot report utility-specific microplastic levels — we note this explicitly in reports.
How to filter microplastics
Not all filters address microplastics. Look for independently certified filters—NSF International certification means the removal claim has been independently verified.
Water ionizers do not remove microplastics — particles pass through the electrolysis cell unchanged. A solid carbon block or RO pre-filter is required for microplastic reduction.
Frequently asked questions
Are microplastics in tap water?
Yes. Multiple studies have detected microplastics in treated tap water in the US and globally. A 2017 Orb Media investigation found microplastic fibres in 83% of US tap water samples tested. The EPA does not currently require utilities to monitor or report microplastics, so utility-specific data is largely unavailable. Bottled water typically contains higher microplastic concentrations than filtered tap water.
Are microplastics in drinking water dangerous?
The research is genuinely early-stage. Microplastics are confirmed in human tissue. A 2024 NEJM study found an association between microplastics in arterial plaques and higher rates of heart attack and stroke — though causation was not established. Animal studies at high concentrations show inflammation and oxidative stress. No dose-response threshold for human health effects from drinking water exposure has been identified. The WHO's current position (2019) is that at present levels microplastics do not appear to pose a risk — though the organisation calls for more research and reduction of plastic pollution.
How do I remove microplastics from drinking water?
Reverse osmosis (NSF 58) is the most reliable method, removing more than 99% of microplastic particles above approximately 0.001 microns. Ultrafiltration membranes also perform well. Solid activated carbon block filters provide partial mechanical removal. Standard pitcher filters have inconsistent performance and are not certified for microplastic removal. Boiling does not remove microplastics.
Does reverse osmosis remove microplastics?
Yes. RO membranes have pore sizes far smaller than microplastic particles. Multiple studies confirm greater than 99% removal by NSF 58 certified RO systems. This is the most reliable household filtration option for microplastics — with the added benefit of also removing PFAS, nitrate, arsenic, and other contaminants.
Is bottled water free of microplastics?
No. Studies consistently find that bottled water contains microplastics — often at higher concentrations than filtered tap water. Plastic bottles and caps shed particles into the water, particularly under heat and UV exposure. From a microplastic exposure standpoint, reverse osmosis or solid carbon-filtered tap water is generally preferable to bottled water.
Is bottled water safer than tap water for microplastics?
No — in most cases the opposite is true. Studies consistently find that bottled water contains higher microplastic concentrations than filtered tap water. A review of over 140 studies found that people who drink only bottled water ingest approximately 90,000 additional microplastic particles per year compared to those drinking tap water. Plastic bottles and caps shed particles into the contents — particularly when exposed to heat or sunlight. A 2026 Ohio State University study found some bottled water brands contain roughly three times more nanoplastic particles than treated tap water. From a microplastic standpoint, reverse osmosis or solid carbon-filtered tap water is the lower-exposure option.
Have microplastics been found in the human brain?
Yes. A 2025 study published in Nature Medicine analysed brain, liver, and kidney tissue from human cadavers and found microplastics present in brain tissue — with concentrations in 2024 samples higher than in 2016 samples, suggesting increasing accumulation over time. Microplastics have also been confirmed in human blood, lung tissue, liver, kidney, placenta, and testes. Whether accumulation causes specific harm at these concentrations is not yet established through causal evidence.
Will the EPA regulate microplastics in drinking water?
In April 2026, the EPA added microplastics to its Contaminant Candidate List (CCL) for the first time — a formal step toward potential future regulation. The CCL is a watch list, not a commitment to act. Few contaminants from previous CCL iterations have been regulated, and no timeline for a microplastics MCL has been set. California adopted a monitoring framework in 2022 — the first in the world — but has not set enforceable limits. Regulation, if it comes, is likely years away.
What are nanoplastics and are they more dangerous than microplastics?
Nanoplastics are plastic particles smaller than 1 micrometre — smaller than most microplastics and harder to detect and measure. Their small size is what makes them of particular concern: nanoplastics can cross biological barriers that larger particles cannot, potentially entering cells and crossing the blood-brain barrier. The 2024 NEJM study that found microplastics in arterial plaques used techniques that also detected nanoplastics. Research on nanoplastics is earlier-stage than microplastics research — the same honest uncertainty applies, but the potential for biological interaction is greater.
Do water treatment plants remove microplastics?
Partially. Conventional water treatment — coagulation, flocculation, sedimentation, and filtration — removes a significant proportion of microplastics from source water before it reaches your tap. Studies suggest conventional treatment removes 70–83% of microplastics. The remaining particles, particularly the smallest ones, pass through. This is why tap water contains fewer microplastics than source water — and why filtered tap water (reverse osmosis, solid carbon block) reduces exposure further at the point of use.
Is microplastics in your water?
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