This content is part of the Nephros Water Institute, an expert-led education program delivering clear insight into waterborne risk, system behavior, and protection strategies across complex facility environments.

In April 2026, the U.S. Environmental Protection Agency (EPA) included microplastics as a priority contaminant group on the draft Contaminant Candidate List 6 (CCL 6) under the Safe Drinking Water Act (SWDA).⁽¹⁾

Microplastics have been the subject of extensive research, and their presence has been documented in drinking water sources around the world. The CCL 6 designation drives “research, funding, and future decisions on regulating emerging threats in public water systems” through the SWDA. And while the EPA’s decision does not set new drinking water standards, it does increase the urgency to better understand and manage the presence and potential impacts of microplastics in drinking water.

For organizations responsible for water quality, that raises questions about plastic particle risk reduction and proven solutions for preventing contamination. If microplastics become a greater focus of monitoring, guidance, and future regulation, what treatment options are available today?

Ultrafiltration is part of the response to plastic particle contamination in drinking water. Through size-based exclusion, ultrafiltration technology is able to physically retain small particulate, such as micro- and nanoplastics (MNPs), that conventional filters cannot retain.

Learn how particle size influences filtration performance and why ultrafiltration has become an important tool for organizations seeking greater control over water-quality risks.

What the EPA’s Draft CCL 6 Means for Microplastics

In announcing draft CCL 6, the EPA described the inclusion of microplastics as a direct response to public concern about contaminants in drinking water. Americans have spent years seeking information about the presence of substances such as plastics and pharmaceuticals and the potential risks they may pose.⁽¹⁾

The announcement also points to why microplastics have become so visible in the public health conversation: these small plastic particles have been found in human blood, breast milk, and organs.⁽¹⁾ Although early clinical studies have few patients and limited MNP exposure assessment data, there are indications that MNPs may be associated with adverse health outcomes.⁽²⁾

Understanding microplastics is no longer confined to environmental research. It’s now closely tied to drinking water quality, risk management, and public confidence in the potable water people use throughout daily life. The implications go beyond the kitchen faucet, encompassing drinking fountains, sinks, showers, ice machines, and other points of use.

Can Microplastics Be Filtered Out?

Filtration is one of the primary methods used to reduce contaminants in water. But microplastics are not a single, uniform contaminant. Plastic particles can vary dramatically in size, which means a filtration technology’s effectiveness depends on what particle sizes it is designed to address.

Understanding the relationship between particle size and filtration performance is the first step in evaluating filter options.

Why Particle Size Matters

Microplastics are commonly defined as particles ranging from 1 micron to 5 millimeters, while nanoplastics are smaller than 1 micron.⁽³⁾

In size-based filtration, particles larger than the membrane pores are physically retained, while smaller particles can pass through. As particle size decreases, the pore size required to capture it needs to be smaller as well.

Many filtration technologies are designed for larger contaminants and may not operate effectively at the nanoscale. Since nanoplastics can be present alongside microplastics in water systems, filtration performance cannot be assumed based on microplastic reduction alone. A technology that performs well against larger plastic particles may not provide the same level of performance for smaller ones.

Why Point-of-Use Filtration Matters

While utilities are responsible for the treatment and delivery of potable water, premise plumbing conditions can change water before it reaches the point of use. As water travels through piping, fixtures, and equipment, new exposure risks can be introduced, making point-of-use filtration an important part of water-quality planning.

Point-of-use filters are designed for installation where water is delivered, including sinks, showers, drinking fountains, ice machines, and other fixtures or equipment. Their placement helps address contaminants where water is actually consumed, dispensed, or used.

With configurations available for plumbing fixtures or direct connection to water lines serving equipment or processes, point-of-use filters can support a broad range of settings. Across healthcare, commercial, industrial, and institutional environments, water-quality needs vary by use, risk profiles, regulatory expectations and operational requirements. Microfiltration, ultrafiltration, and other point-of-use technologies allow solution selection based on the contaminants of concern, from microorganisms to fine particulate matter, including MNPs.

How Ultrafiltration Supports Microplastic, Nanoplastic & Broader Contaminant Control

Micro- and nanoplastics add a new dimension to drinking water management. As a membrane-based treatment that operates at the nanoscale, ultrafiltration is relevant not only to these emerging plastic particle concerns but also to established microbial-control applications involving bacteria, viruses, endotoxins, and other harmful contaminants.

When evaluating solutions, begin with the risk being addressed: the contaminants of concern, particle sizes, and points of exposure. Assess the available technology against these needs, considering the membrane pore size, performance data, intended use, and application fit. This approach ensures alignment between filtration solutions and specific contaminant risk and supports targeted water-quality management as emerging concerns continue to evolve.

Preparing for the Next Stage of Water-Quality Risk

The EPA’s microplastics CCL 6 designation reminds us that water-quality priorities do not remain static. As research, regulatory guidance, best practices, and treatment technologies advance, organizations may need to make decisions with incomplete information.

Still, this development is part of a larger push toward more proactive and precise water-quality management. Preparedness means identifying and implementing protection at critical points, while balancing safety, operational requirements, and long-term planning amid uncertainty.

Point-of-use ultrafiltration can support these efforts, offering a technology already operating at the scale required to retain both microplastics and nanoplastics.

Explore the Nephros Water Institute for more educational resources on water quality, point-of-use protection, regulatory developments, and water safety planning.

Sources:

(1) U.S. Environmental Protection Agency, “EPA Takes Bold Action to Ensure Drinking Water is Safe from Microplastics, Pharmaceuticals, and Potential Hidden Contaminants,” News Release (April 2, 2026). https://www.epa.gov/newsreleases/epa-takes-bold-action-ensure-drinking-water-safe-microplastics-pharmaceuticals-and

(2) Lamoree, M.H. et al., “Health impacts of microplastic and nanoplastic exposure,” Nature Medicine 31, 2873–2887 (2025). https://www.nature.com/articles/s41591-025-03902-5

(3) Ali, N. et al., “Microplastic and nanoplastic pollution and associated potential disease risks,” The Lancet Planetary Health 9(12), 101390 (2025). https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(25)00268-2/fulltext

(4) U.S. Environmental Protection Agency, “Drinking Water Contaminant Candidate List 6 — Draft,” Federal Register 91 FR 17186 (April 6, 2026). https://www.epa.gov/ccl/draft-contaminant-candidate-list-6-ccl-6

(5) Li, R. et al., “Microplastics and nanoplastics in brain tumours and the healthy human brain,” Nature Health (2026). https://www.nature.com/articles/s44360-026-00091-4

(6) Ghiyamihoor, F. et al., “Micro- and Nanoplastics in the Human Brain: Mechanistic Plausibility, Translational Challenges, and Links to Neurological Disease Trends,” Molecular Neurobiology 63, 598 (2026). https://link.springer.com/article/10.1007/s12035-026-05895-9

(7) Pérez-López, A. et al., “Micro- and nanoplastics removal from water and solid matrices: Technologies, challenges, and future perspectives,” Environmental Research 299:124295 (2026). https://pubmed.ncbi.nlm.nih.gov/41856237/