Microplastics in drinking water

Microplastics are one of the newest questions in drinking water, and one of the most honest answers a company can give is that the science is still being written. What researchers agree on already is striking enough: these particles are now found almost everywhere water is, including tap water, and in even higher numbers in the bottled water many people buy to avoid the tap.

What microplastics and nanoplastics are

Microplastics are plastic fragments smaller than five millimeters, down to sizes invisible to the eye. Below about one micrometre they are called nanoplastics, and their small size is exactly why they matter: the smaller a particle, the more easily it can pass through filters, and potentially through biological barriers in the body. They come from the slow breakdown of larger plastic waste, from synthetic textiles, tire wear, and from plastic packaging and pipes.

They're in tap water, and more so in bottled water

A widely cited 2018 study that tested bottled water from around the world found microplastics in the large majority of samples, at roughly twice the concentration typically found in tap water. People reaching for bottled water to sidestep plastic were, on average, drinking more of it.

The picture got sharper in 2024. Using a new laser-based imaging technique, researchers at Columbia and Rutgers (publishing in the journal PNAS) estimated that a liter of bottled water contains on the order of 240,000 plastic particles, the vast majority of them nanoplastics, roughly ten to a hundred times more than earlier methods had been able to detect. The plastic came in part from the bottle and cap themselves.

It adds up to a number that is hard to unsee. A widely cited 2019 analysis by the University of Newcastle, commissioned by the World Wildlife Fund, estimated that the average person may ingest around five grams of plastic a week, roughly the weight of a credit card, from water and food combined. Researchers still debate the exact figure, but even as an estimate it reframes the question: this is not a trace exposure most people can safely ignore.

What we know about the health effects, and what we don't

This is where honesty matters. The World Health Organization reviewed the evidence in 2019 and concluded that, based on the limited data available at the time, microplastics in drinking water did not appear to pose a health risk at typical levels, while stressing major gaps in the research and calling for more study. That remains roughly the state of formal guidance.

Since then, the findings have grown harder to ignore. Researchers have now detected microplastics in human blood, lungs, and placenta. A 2024 study published in the New England Journal of Medicine found micro- and nanoplastics in the fatty plaque of patients' arteries, and reported that those patients had a higher rate of heart attack, stroke or death over the following years. That is an association, not proof that the plastic caused the harm, and scientists are careful to say so. But the direction of the research is a reasonable cause for caution rather than panic.

Are they regulated?

Not yet, at the federal level, there is no national enforceable limit (MCL) for microplastics in U.S. drinking water. California has moved first, becoming the first place in the world to require monitoring of microplastics in drinking water so that data can be gathered. For now, "no violation" on a water report tells you nothing about microplastics, because they are not on the test.

How to reduce microplastics in your water

Reverse osmosis (RO)

An RO membrane has pores far smaller than microplastic particles, and small enough to reject the great majority of nanoplastics as well. That makes an under-sink reverse-osmosis system one of the most effective ways to reduce plastic particles in the water you drink and cook with.

High-quality carbon block filtration

A dense carbon block filter physically strains out larger microplastic particles while also improving taste and reducing chlorine, a useful layer, though not as complete as RO for the smallest particles.

And, simply, drink filtered tap over bottled

Given what the 2024 research showed about bottled water, filtering your own tap water at home is not only cheaper and greener, it may mean fewer plastic particles in your glass, not more. A softener, worth noting, does not remove microplastics; it addresses hardness. Reverse osmosis is the tool for this job.

Microplastics are a developing story, and we would rather tell you that plainly than overstate what is known. What is clear is that they are present, that bottled water is not the escape it seems, and that good filtration meaningfully reduces them. A free in-home water assessment is a sensible first step toward drinking water you feel genuinely good about.