Every week, the average American ingests about five grams of plastic — roughly a credit card's worth. That finding, published by the University of Newcastle in 2019 and since confirmed by multiple peer-reviewed studies, should have changed how we think about water treatment. It mostly didn't.
Microplastics — particles smaller than five millimeters, often invisible to the naked eye — are now found in virtually every water source on Earth. Tap water, bottled water, groundwater, rainwater. A 2024 study in the Proceedings of the National Academy of Sciences found an average of 240,000 nanoplastic particles per liter of bottled water, roughly 100 times more than previous estimates that only measured microplastics.
How They Get There
The sources are everywhere. Synthetic clothing sheds fibers every wash cycle — a single load of laundry releases up to 700,000 microfibers into wastewater. Tire wear on roads generates an estimated 6.1 million tons of tire-wear particles globally each year, much of it washing into storm drains and surface water. Plastic packaging degrades. Agricultural plastic mulch breaks down in soil and migrates to groundwater.
Wastewater treatment plants catch some of it — up to 90% in tertiary treatment systems. But "90% of a very large number" still leaves enormous quantities passing through. And the captured particles? They concentrate in biosolids, which are then spread on agricultural land, restarting the cycle.
Stormwater is an even bigger gap. Most stormwater in America receives zero treatment before entering rivers, lakes, and aquifers that serve as drinking water sources. Every rainstorm washes a fresh load of microplastics directly into the water supply.
What They Do to You
The honest answer is: we're still finding out, and the early data is concerning.
A landmark 2024 study published in the New England Journal of Medicine found that patients with microplastics and nanoplastics detected in their carotid artery plaque had a 4.5 times higher risk of heart attack, stroke, or death over a 34-month follow-up period. That's not a subtle correlation — that's a major signal.
Laboratory studies show microplastics cause inflammation, oxidative stress, and cellular damage. They act as vectors for other contaminants — PFAS, heavy metals, pesticides, and endocrine disruptors adsorb onto plastic particle surfaces and hitch a ride into your body. A 2023 study in Environmental Science & Technology found that microplastics in drinking water carried measurable concentrations of lead, cadmium, and phthalates.
The World Health Organization's 2022 report on microplastics in drinking water acknowledged the evidence gaps but noted that "the potential for adverse health effects warrants a precautionary approach." In plain language: we can't prove they're safe, and the evidence increasingly suggests they're not.
What Utilities Aren't Doing
Here's the uncomfortable reality: the EPA has no regulatory standard for microplastics in drinking water. None. There's no Maximum Contaminant Level, no monitoring requirement, no treatment mandate. Most water utilities in America don't test for microplastics at all — not because they don't exist in the water, but because nobody requires them to look.
California became the first state to mandate microplastic monitoring in drinking water in 2024, requiring the state's largest utilities to begin testing by mid-2026. The results will likely be illuminating — and uncomfortable.
Conventional water treatment wasn't designed for particles this small. Sand filtration catches some. Coagulation and flocculation help with larger microplastics. But nanoplastics — particles smaller than one micrometer — pass through most treatment systems entirely. Advanced methods like ultrafiltration, reverse osmosis, and granular activated carbon can remove the majority of micro- and nanoplastics, but these systems are expensive and primarily found in newer or well-funded utilities.
The gap between what we know exists in drinking water and what we require utilities to do about it is vast.
The Bottled Water Illusion
Switching to bottled water isn't the answer. The PNAS study found dramatically higher plastic particle counts in bottled water than tap water — largely from the plastic bottles themselves. Every time a plastic bottle is exposed to heat, UV light, or simple mechanical stress, it sheds particles into the water inside.
The irony is sharp: people buying bottled water to avoid contaminants are often increasing their microplastic exposure in the process.
What Actually Helps
At the individual level, point-of-use filtration makes a meaningful difference. Reverse osmosis systems and high-quality activated carbon filters can remove the majority of microplastics from tap water. Glass and stainless steel containers eliminate the packaging-to-water contamination pathway.
But individual action can't solve a systemic problem. We need three things:
Monitoring standards. You can't manage what you don't measure. The EPA needs to establish standardized testing protocols for microplastics in drinking water and require utilities to report results. California's mandate should be the floor, not the ceiling.
Treatment upgrades. As water systems modernize — and they must, given the age of American water infrastructure — microplastic removal capability should be part of the design specification, not an afterthought.
Source reduction. The most effective treatment is prevention. Extended producer responsibility laws, synthetic fiber capture requirements for washing machines (France already mandates this by 2025), and stormwater treatment standards would reduce the load before it reaches the treatment plant.
Where EPR Foundation Stands
We believe Americans have a right to know what's in their water — all of it, not just the contaminants regulators have gotten around to regulating. Microplastics are in your drinking water right now. The question isn't whether exposure is happening. It's whether we're going to acknowledge it, measure it, and do something about it before the health data forces our hand.
The science is early but directional. The exposure is universal and increasing. The regulatory response is essentially nonexistent. That's a familiar pattern in environmental health — and historically, it hasn't ended well for the people drinking the water.