What Are Microplastics?

Microplastics are small plastic particles generally measuring less than 5 millimeters in at least one dimension. That's roughly the size of a sesame seed at the upper end, although many of the particles studied in drinking water are far smaller and cannot be seen with the naked eye.

Microplastics aren't one particular chemical. They can be fragments, fibers, films, beads, or other shapes made from many different types of plastic.

Primary vs. secondary microplastics

Primary microplastics are manufactured at a small size, such as certain plastic raw materials used in manufacturing.

Secondary microplastics form when larger plastic products gradually break down. Sunlight, heat, friction, weathering, washing, and ordinary use can cause plastics to fragment into progressively smaller particles.

Common environmental sources include:

• Breakdown of plastic packaging and other discarded products
• Synthetic fibers released from clothing
• Tire and road wear
• Paints and coatings
• Plastic manufacturing and industrial materials
• Household plastic products as they wear

What about nanoplastics?

Nanoplastics are even smaller plastic particles. Definitions are still evolving, but they are commonly described as particles smaller than approximately one micrometer.

For comparison, a human hair is roughly 70 micrometers wide.

This distinction matters. Smaller particles are harder to detect, harder to study, and potentially behave differently from larger microplastics. Advances in laboratory technology are also one reason newer studies sometimes report more particles than older studies dramatically: researchers can now detect particles that earlier methods missed.

How Do Microplastics Get Into Drinking Water?

Microplastics can move through the environment by air, stormwater runoff, wastewater, rivers, lakes, soil, and groundwater.

For example, rain can wash particles from roads and urban surfaces into streams and reservoirs. Synthetic fibers released during laundry can enter wastewater. Lightweight fibers can also travel through the air before settling onto land or water.

That means drinking water is one part of a much larger environmental cycle.

What happens at a municipal water treatment plant?

Conventional drinking-water treatment wasn't originally designed specifically for microplastics. Nevertheless, treatment processes that remove suspended material can also capture many plastic particles.

Processes such as coagulation, sedimentation, and filtration may reduce microplastics before treated water enters the distribution system.

There is no meaningful universal removal percentage, however. Performance can depend on:

• Particle size
• Particle shape
• Plastic type
• Treatment technology
• Water chemistry
• Plant operating conditions

This is particularly important for very small particles and nanoplastics, which present greater measurement and treatment challenges.

Tap Water vs. Bottled Water: Which Has More Microplastics?

If your goal is to avoid microplastics, switching automatically from tap water to bottled water isn't a guaranteed solution.

Studies have detected plastic particles in both.

A widely discussed 2018 study detected synthetic polymer contamination in bottled water from multiple countries. In 2024, researchers using a much more sensitive imaging technique reported far higher numbers of micro- and nanoplastic particles in bottled water than many earlier studies had detected.

Those results don't necessarily mean bottled water suddenly became more contaminated. They demonstrate an important problem in microplastics research: the smaller the particles a laboratory can detect, the more particles it is likely to count.

Are Microplastics in Drinking Water Harmful?

This is the most important question—and currently the one science cannot answer with a simple yes or no.

Scientists have established that humans are exposed to microplastics and nanoplastics through food, beverages, air, and the broader environment. Researchers have also reported plastic-associated material in human samples and tissues.

What has not yet been established is exactly what typical long-term exposure means for human health.

What laboratory studies have found

Experiments involving cells and animals have reported biological responses under certain conditions, including inflammation, oxidative stress, altered immune signaling, and other effects.

These studies help researchers identify possible biological mechanisms. They do not automatically demonstrate that the same effects occur in humans at typical environmental exposure levels.

What about studies in humans?

A major 2024 study published in the New England Journal of Medicine examined patients undergoing surgery for carotid artery disease. Researchers reported an association between detectable micro- and nanoplastics in arterial plaque and a higher rate of subsequent cardiovascular events.

The study attracted considerable attention because it combined tissue analysis with patient outcomes.

However, it was an observational study. It did not establish that the detected particles caused heart attacks, strokes, or deaths. Questions about contamination control and other methodological limitations have also been raised in the scientific literature.

What does the FDA currently say?

The FDA acknowledges that microplastics and nanoplastics can enter the food supply through environmental pathways. The agency currently says that available scientific evidence does not demonstrate that the levels detected in foods pose a human health risk.

The FDA also emphasizes a major limitation of the research: scientists still lack fully standardized methods for detecting, measuring, and characterizing microplastics and nanoplastics.

In other words, the appropriate conclusion isn't that microplastics have been proven harmless—or that they have been proven to cause widespread disease. Important scientific uncertainties remain.

Can Water Filters Remove Microplastics?

Some water treatment and filtration technologies can reduce particles within specific size ranges. But "microplastics" encompasses such a broad range of sizes that there isn't a single removal percentage that applies to every filter and every plastic particle.

Different filtration technologies work differently:

Why particle size matters

A claim that a filter "removes microplastics" can sound more definitive than it really is.

A 1-millimeter plastic fragment and a submicron particle can both fall under the category of microplastics, yet they present completely different filtration challenges.

When comparing filtration products, look beyond the headline percentage and ask:

• What particle size was actually tested?
• Was the testing performed by an independent laboratory?
• What test method was used?
• Was performance evaluated over the element's service life?
• Can you review the actual performance information?

These questions tell you considerably more than a broad "microplastic removal" claim.

Choosing a Home Water Filter for Everyday Drinking Water

Microplastics may be one concern, but they probably aren't the only reason you're considering a water filter.

Your household may also care about chlorine taste and odor, lead, PFAS, VOCs, disinfection byproducts, or other substances associated with the local water supply.

That's why choosing a filter solely for its broad microplastics claim can be misleading.

A better approach is to:

1. Understand your water source. Review your local utility's water-quality report if you use municipal water.
2. Identify the contaminants you actually want to address.
3. Compare filtration technologies.
4. Review contaminant-specific testing and certification information.
5. Consider capacity, maintenance, installation, and operating cost.

For a broader starting point, see our Drinking Water Contaminants Reference Guide.

Where a Berkey® System Fits

For households that prefer a gravity-fed countertop system, Berkey® systems offer an alternative to under-sink reverse osmosis and permanently installed filtration systems.

Berkey® stainless-steel systems require no electricity and no plumbing connection. Water is poured into the upper chamber and moves through the installed filtration elements by gravity.

This can also make filtered tap water convenient for households trying to reduce their routine use of single-use bottled water.

Choose a Berkey® size for your household

Compare Berkey® Water Filter Systems

7 Practical Ways to Reduce Microplastic Exposure at Home

Completely avoiding microplastics isn't realistic. A more practical goal is to reduce unnecessary exposure when it is simple to do so.

None of these measures eliminates microplastics. They are simply reasonable ways to reduce avoidable contact while research continues.

Does the EPA Regulate Microplastics in Drinking Water?

There is currently no federal Maximum Contaminant Level (MCL) specifically for microplastics in U.S. drinking water.

However, the regulatory picture is changing.

On April 2, 2026, the U.S. Environmental Protection Agency announced its draft Sixth Contaminant Candidate List (CCL 6). For the first time, the draft includes microplastics as a contaminant group.

That is significant, but it does not mean EPA has established a microplastics drinking-water limit.

The EPA says important data gaps remain before the agency can fully understand the health risks associated with microplastics in drinking water.

CCL inclusion therefore represents an important step in federal evaluation—not an enforceable limit on public water systems.

Why Do Microplastics Studies Report Such Different Numbers?

You may see one headline reporting hundreds of particles per liter and another reporting hundreds of thousands. That doesn't necessarily mean one study is wrong.

Imagine two people searching the same beach for shells. One counts only shells larger than a coin. The other counts everything down to grains of sand. Their totals will be dramatically different even though they searched the same beach.

Microplastics research has a similar problem.

Results can vary because laboratories use different:

• Minimum particle sizes
• Sample volumes
• Collection procedures
• Identification techniques
• Contamination controls
• Reporting methods

Methods such as FTIR spectroscopy, Raman spectroscopy, and pyrolysis-GC/MS can answer different analytical questions and have different capabilities.

The important question isn't simply "How many particles did the study find?" It is also "What sizes and types of particles was the study capable of detecting?"

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