Microplastics in Tap and Bottled Water: What the Research Shows and What to Do

Updated September 2026

Microplastics, plastic fragments smaller than 5 millimeters, have been found in both tap water and bottled water in every major study conducted so far. If you've assumed bottled water is the cleaner option, the data says otherwise: bottled water has consistently tested higher for microplastic contamination than tap water. Here's what the research actually found, where these particles come from, and what you can realistically do about it.

How Much Microplastic Is in Tap Water?

The most widely cited data on this comes from a 2017 investigation by Orb Media, a Washington D.C.-based journalism group, in partnership with researchers Dr. Sherri Mason of the State University of New York at Fredonia and Elizabeth Wattenberg of the University of Minnesota's School of Public Health. Research scientist Mary Kosuth analyzed 159 tap water samples collected across 14 countries on five continents, including the US, UK, and Ireland.

The results: 83% of the samples tested positive for microplastic fibers, with contamination ranging from 72% of samples in Europe to as high as 94% in the US.

"Scientists say they don't really know how these microplastics reach our taps or what the health risks might be," said Molly Bingham, founder of Orb Media, at the time of the report's release.

How Much Microplastic Is in Bottled Water?

Orb Media followed up with a second investigation focused specifically on bottled water. A team led by Dr. Mason tested 259 bottles from nine countries and 11 different brands, using the Nile Red method, a dye-based technique that makes plastic particles fluoresce under specific lighting so they can be counted.

The result was worse than the tap water findings: 93% of the bottled water samples contained microplastics, averaging 325 particles per liter, roughly double the concentration found in the tap water study. Independent scientists who reviewed the methodology, including Dr. Andrew Mayes at the University of East Anglia, who helped develop the Nile Red technique, and Michael Walker, a former board member of the UK Food Standards Agency, both described the approach as sound, though the report itself has not been published in a peer-reviewed journal.

Where Do These Microplastics Come From?

For tap water, researchers point to several sources feeding into the water supply:

• Fibers shed from synthetic clothing during washing, which enter wastewater
• Airborne synthetic fibers released through everyday fabric wear
• Tire dust washed off roads into waterways
• Paint dust from road markings and buildings
• Larger plastic products breaking down into smaller fragments over time
• Microbeads from certain cosmetic products

For bottled water specifically, researchers believe the bottle and cap themselves are a major contributor. Bottle caps are commonly made from polypropylene, and the act of twisting a cap open may shed particles directly into the water. The bottling process is a suspected secondary source.

Is Bottled Water Actually Safer Than Tap Water?

Not based on this data, and not as a general rule either. In the US, tap water is regulated by the EPA, while bottled water is regulated by the FDA, and according to the Mayo Clinic, the two are generally comparable in terms of safety. The decision between them mostly comes down to taste preference, convenience, and cost, not a clear safety advantage for either one. When it comes specifically to microplastics, the data above shows tap water tested cleaner than bottled in the same research.

What About Filtering Microplastics at Home?

Black Berkey and Berkey Phoenix elements are rated to filter down to the sub-micron range, well below the roughly 10-micron fiber diameter measured in the Orb Media tap water study, so particles in that size range have a hard time getting through. Neither element has been lab-tested for microplastics specifically, though, so we don't publish a removal percentage. What the sub-micron rating does and doesn't tell you, and how Berkey compares with carbon block and reverse osmosis on this question, is covered on our dedicated page: Can Berkey Remove Microplastics From Water?

What You Can Do to Reduce Microplastic Exposure

1. Skip single-use plastic bags. Bring a reusable bag when you shop.
2. Skip plastic straws. Use a reusable metal or silicone straw if you want one at all.
3. Wash synthetic fabrics less often, and use a laundry filter designed to catch microfibers before they reach wastewater.
4. Carpool or use public transit when practical, to cut down on tire dust from road wear.
5. Choose a non-plastic toothbrush, such as bamboo, over a plastic one.
6. Rinse paint brushes into a container, not the sink, and dispose of the rinse water properly.
7. Carry a reusable, filtered water bottle instead of buying bottled water. It cuts down on plastic waste and addresses the water you're actually drinking, rather than adding another bottled-water variable to the mix.

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