It's a question many of us have pondered while refilling a glass from the tap or reaching for a bottled drink: just how much plastic are we actually consuming? The truth, as it turns out, is a bit unsettling given recent findings. Studies suggest that on average, we're ingesting about 5 grams of plastic every week – roughly the weight of a credit card. Let that sink in for a moment.
Microplastics are everywhere. They are tiny plastic particles, generally less than 5 millimeters in length, that result from the breakdown of larger plastic products or are manufactured directly for specific applications, like microbeads in cosmetics. Because of their size and persistence, they have infiltrated nearly every ecosystem on Earth, from the deepest oceans to the highest mountains, and yes, our drinking water.
The scientific community is still grappling with the full scope of health implications. What we do know is that these particles can carry harmful chemicals, including phthalates and bisphenols (like BPA), which are known endocrine disruptors. When ingested, microplastics can potentially release these chemicals into our bodies. Beyond chemical exposure, there's also concern about physical damage to tissues and organs, and the potential for microplastics to cross biological barriers, such as the gut lining or even the blood-brain barrier. The World Health Organization (WHO) has recognized the need for more research into the human health effects of microplastics, emphasizing that while current evidence doesn't indicate an immediate health risk, the long-term impacts are largely unknown and warrant careful investigation (WHO, 2019).
For years, bottled water has been marketed as a purer, safer alternative to tap water. This perception has led to a booming industry, with global sales soaring. However, the convenience and perceived purity come with a hidden cost: microplastics.
In a landmark study published in Environmental Science & Technology in 2018, researchers at the State University of New York at Fredonia analyzed 259 bottles of water from 11 different brands purchased in nine different countries. They found microplastic contamination in 93% of the samples. The average concentration was 325 plastic particles per liter, with some individual bottles containing thousands. Polypropylene, a common plastic used in bottle caps, and polyethylene terephthalate (PET), the material most bottled water bottles are made from, were the most prevalent types of microplastics identified.
A more recent study by Columbia University Lamont-Doherty Earth Observatory and Rutgers University in 2024, published in the Proceedings of the National Academy of Sciences, found an even more concerning level of contamination: an average of 240,000 plastic fragments per liter in popular bottled water brands. This study uniquely identified nanoplastics, particles even smaller than microplastics, which can be even more insidious due to their ability to penetrate cells and cross biological barriers. Their technique used stimulated Raman scattering microscopy, offering a much more detailed view of these minuscule plastic contaminants. The implication here is that the smaller the plastic, the more bioavailable it could be, meaning it's more likely to be absorbed into our bodies and potentially cause harm.
So, if you're reaching for bottled water thinking it's the cleaner choice, the data points the other way.
On microplastics specifically, bottled water tends to be the bigger source, not the smaller one. The reasons are built into the product. The bottle and cap are themselves plastic (usually PET and polypropylene), and they shed particles into the water the moment they're made, and more so with heat, sunlight, agitation, and time on a warm truck or shelf. Every time you crack the cap or squeeze the bottle, you release more. That 2024 Columbia study's headline number, roughly 240,000 fragments per liter, dwarfs typical tap-water counts.
Tap water isn't microplastic-free. But it usually carries far fewer plastic particles than bottled, and it hasn't spent weeks marinating in a plastic container. It's also cheaper by orders of magnitude, and in the U.S. it's tested against enforceable standards that bottled water, regulated as a packaged food, isn't held to in the same way.
There's an important caveat: this comparison is about microplastics. If your tap water has a different problem, like lead from old pipes, high PFAS, or a boil-water advisory, that changes the calculation, which is exactly why testing your own water beats assuming either source is safe.
Generally, yes. Studies have found bottled water carries substantially more plastic particles than typical tap water, because the plastic bottle and cap shed particles into the water over time and with handling. A 2024 Columbia study measured an average around 240,000 fragments per liter in popular bottled brands.
No. Microplastics have been found in tap water worldwide. But the counts are usually far lower than in bottled water, and a good filter reduces them further.
Filter your tap water (reverse osmosis is most effective) and store it in glass or stainless steel. Avoid single-use plastic bottles, and never heat food or water in plastic, since heat increases shedding.
Taste reflects minerals and disinfectant, not plastic content. Bottled water is often demineralized for a neutral taste, but that has nothing to do with how many microplastic particles it contains.
Check your water quality by zip code to see what contaminants have been found in your water. Find water filters that remove PFAS – reverse osmosis and carbon block systems also reduce microplastics. Microplastics aren't the only invisible threat – read our PFAS contamination guide to learn about forever chemicals.
Check your water now. Enter your zip code at KnowYourExposure.com to see what contaminants have been detected in your local water supply – including PFAS, lead, and other regulated compounds.