People may be exposed to microplastics through the air they breathe, the food they eat, the water they drink, and adsorption through the skin. Researchers report finding microplastics in the bodies of humans and animals. How microplastics enter the body is not well understood.

Research to determine how much exposure to microplastics leads to negative human health effects is still in its early stages. Microplastics are a diverse group of plastic particles with a mixture of physical and chemical compositions. Understanding whether microplastics are a health concern will require research considering the size, shape, chemical composition, and other aspects of the microplastics that we ingest when we drink water, as well as how much we ingest and how long they remain in the human body.

According to the Food and Drug Administration, microplastics are frequently found in the environment, including marine water, wastewater, fresh water, food, air and drinking water, including both bottled water and tap water. Data on the levels of microplastics in our drinking water are limited. The studies that we do have often use different methods and tools to sample and analyze microplastic particles.

The World Health Organization identifies surface run-off and wastewater effluent as the two main sources of microplastics in water supplies. Better data are required to identify specific sources and quantify the amount of microparticles being released. Investigation suggests that plastic materials piping and home plumbing can release microplastics to drinking water; to-date observed levels have been very low. By comparison research indicates that plastic bottles and caps may be significant sources of microplastics in bottled water.

In the United States, microplastics are not currently regulated in drinking water. The United States Environmental Protection Agency (EPA) is responsible for implementing the Safe Drinking Water Act (SDWA). In 2026, EPA proposed adding microplastics to Contaminant Candidate List 6 (CCL6). Including a contaminant on the CCL makes that contaminant a priority for data collection and research needed to support decisions to regulate.

In the United States setting drinking water standards for any contaminant, including microplastics, requires careful consideration of available information to determine if the contaminant occurs in drinking water frequently enough and at levels that pose a concern to human health. Prior to regulating a contaminant it must also be clear that there are steps public water systems can take that will provide real public health benefits.

An important step in obtaining data to support decisions to regulate is collecting contaminant occurrence data. Every five years, EPA issues new instructions for monitoring contaminants that are not yet regulated using the Unregulated Contaminant Monitoring Rule (UCMR). Microplastics may be included in a future UCMR cycle. In order to include microplastics on the UCMR, EPA will need appropriate and standardized methods for sampling and quantifying the microplastics in the required samples. Sampling procedures and analytical methods for microplastics are currently in development.

Microplastics can be found in drinking water in homes relying on private wells. There are not regulations or recommended health guidelines for microplastics in drinking water to guide homeowners relying on private wells in making decisions to test or treat water at their homes.

If you are concerned about microplastics in your drinking water, you may want to consider purchasing a home treatment device. However, in order to make a well-informed and cost-effective decision, consider checking with your water system or reading your water system’s annual water quality report to learn about your water system’s source water and treatment systems.

Your water system may also be able to help you understand water quality considerations should you want to select a treatment device for microplastics.

Importantly, there are independent certifying organizations that ensure home water treatment devices meet contaminant removal claims. Always consider installing certified home water treatment products. NSF International, the Water Quality Association, Underwriters Laboratories and CSA International certify home water treatment devices.

If you choose to use a home water treatment device, it is very important to follow the manufacturer's operation and maintenance instructions carefully in order to make sure the device works properly.

Research conducted at Columbia University, and supported by the National Institutes of Health, found that a liter of bottled water had about 240,000 tiny pieces of plastic in it, including approximately 90% nanoplastics.