The U.S. Environmental Protection Agency made history on April 2, 2026, when it published the Draft Sixth Contaminant Candidate List (CCL 6) in the Federal Register. For the first time, the agency formally classified microplastics as a contaminant group requiring focused research and potential future regulation under the Safe Drinking Water Act (SDWA).

This move signals a major shift in how the federal government views the invisible plastic particles now found in virtually every water source — from mountain springs to municipal taps. Combined with newly enforced PFAS limits also taking effect in 2026, American drinking water is entering a new regulatory era.

Here is what you need to know about EPA CCL 6, why microplastics matter, and what water treatment systems are proven to remove them.

What Is the EPA Contaminant Candidate List (CCL)?

The Contaminant Candidate List is a roster of unregulated chemicals and microbes that EPA scientists believe may pose a risk to public health via drinking water. Substances on the CCL are not yet regulated — but their inclusion triggers focused research, data collection, and a formal scientific review that can lead to enforceable Maximum Contaminant Levels (MCLs) years down the road.

The CCL is updated every five years under SDWA requirements. Previous lists included chemicals such as perchlorate, chromium-6, and PFAS — all of which later received regulatory attention. The CCL pipeline has proven to be a reliable early-warning system for emerging threats.

• CCL 1 (1998): 60 chemicals, 10 microbes — led to regulation of several disinfection byproducts
• CCL 2 (2005): 51 chemicals — flagged perchlorate, prompting health advisory guidance
• CCL 3 (2009): 116 chemicals — included pharmaceuticals for the first time as individual compounds
• CCL 4 (2016): 97 chemicals — added cyanotoxins and strontium
• CCL 5 (2022): Included PFAS as a group, paving the way for the 2024 PFAS MCL rule
• CCL 6 (Draft, April 2026): Adds microplastics and pharmaceuticals as groups — a significant methodological shift

What the EPA Announced on April 2, 2026

The Draft CCL 6 published by EPA marks two historic firsts:

1. Microplastics listed as a contaminant group — rather than individual plastic compounds, the EPA is treating microplastics collectively. This acknowledges the analytical challenge: thousands of plastic polymer types exist, and standardized detection methods are still being developed.
2. Pharmaceuticals listed as a contaminant group — building on CCL 3 and 5 work, the agency is expanding its pharmaceutical monitoring scope to include hormones, antibiotics, and other drug residues that pass through conventional wastewater treatment.

The announcement opened a 60-day public comment period ending June 2, 2026. EPA is expected to finalize CCL 6 by November 17, 2026, following consultation with its independent Science Advisory Board (SAB).

Importantly, the U.S. Department of Health and Human Services (HHS) simultaneously announced a $144 million investment in a new microplastics research program — measuring plastics in human tissue, evaluating health impacts, and exploring removal technologies. This coordinated federal action signals that microplastics regulation, while still years away, is now on an accelerated track.

“EPA is taking bold action to ensure drinking water is safe from microplastics, pharmaceuticals, and potential hidden contaminants.”

U.S. Environmental Protection Agency, April 2, 2026

Why Microplastics in Drinking Water Are a Serious Concern

Microplastics — generally defined as plastic particles smaller than 5 millimeters — have been detected in virtually every water source tested globally, including deep ocean samples, Arctic ice cores, and remote mountain springs. Research published in peer-reviewed journals has detected them in human blood, lung tissue, breast milk, and even fetal placental tissue.

Sources of Microplastics in Water

• Plastic degradation: Bottles, packaging, and synthetic textiles break down into micro and nano-scale fragments over time through UV exposure and mechanical wear
• Wastewater effluent: Conventional municipal wastewater treatment removes approximately 70–80% of microplastics, but the remainder enters surface water
• Stormwater runoff: Road runoff carries tire rubber particles, synthetic fibers from clothing, and fragmented single-use plastics into waterways
• Agricultural sources: Plastic mulch film, irrigation pipes, and biosolid application introduce plastics directly into soil and groundwater

Known and Suspected Health Effects

The scientific consensus on microplastic health effects is still developing, but the weight of evidence is growing. Key concerns include:

Health Concern	Mechanism	Status of Evidence
Inflammation	Physical irritation from particles in tissues	Animal studies strong; human studies ongoing
Endocrine disruption	Leaching of plasticizers (phthalates, BPA) from plastic particles	Well-documented for specific compounds
Oxidative stress	Free radical generation from nano-plastic fragments	Laboratory evidence; human data limited
Gut microbiome disruption	Accumulation in intestinal tissue	Emerging — 2024-2025 studies
Cardiovascular risk	2024 NEJM study linked plaque microplastics to heart attack/stroke risk	Significant — human cohort data

A landmark 2024 study published in the New England Journal of Medicine found microplastics and nanoplastics in arterial plaque samples and linked their presence to a 4.5-fold increased risk of heart attack, stroke, or death over a three-year follow-up period — the first major human clinical evidence connecting microplastics to cardiovascular outcomes.

Microplastics and PFAS: A Dual Regulatory Challenge in 2026

The CCL 6 microplastics announcement comes alongside the implementation of the EPA’s first-ever enforceable PFAS limits, which took effect in 2024 and require public water systems to comply by 2027:

• PFOA and PFOS: Maximum Contaminant Level (MCL) set at 4 parts per trillion (ppt)
• PFHxS, PFNA, HFPO-DA: MCL at 10 ppt each
• EU Drinking Water Directive: Requires PFAS monitoring beginning in 2026 across all EU member states

The global PFAS treatment market is projected at $2.1 billion in 2026, growing to $3.4 billion by 2033 as regulations tighten worldwide. Microplastics regulation is expected to follow a similar trajectory — starting with candidate listing, progressing to monitoring requirements, and ultimately leading to MCLs.

For water treatment facility operators and building owners, the lesson from PFAS is clear: begin evaluating microplastic removal capacity now, before binding regulations force rushed compliance.

Can Water Treatment Systems Remove Microplastics?

The good news: reverse osmosis systems and ultrafiltration membranes can effectively remove microplastics from drinking water. The key factor is membrane pore size relative to particle size.

Reverse Osmosis (RO) — Most Effective Method

Reverse osmosis membranes have pore sizes of approximately 0.0001 microns (1 angstrom) — far smaller than even the smallest microplastic particles. RO membranes remove:

• Microplastics (5mm down to 1 micron) — 99%+ removal
• Nanoplastics (below 1 micron) — high removal efficiency
• PFAS compounds — simultaneous removal at >95% efficiency
• Heavy metals, dissolved solids, bacteria, and viruses

Commercial and industrial reverse osmosis systems from AMPAC USA are engineered for applications from small-scale point-of-use to large-scale municipal treatment. Our systems process water at commercial capacity while meeting or exceeding NSF/ANSI 58 standards for contaminant reduction.

Ultrafiltration (UF) and Nanofiltration (NF)

Ultrafiltration membranes (pore size 0.01–0.1 microns) remove microplastics >0.1 microns effectively, but allow smaller nano-scale particles to pass. Nanofiltration (0.001 microns) bridges the gap between UF and RO. Both technologies are used in municipal pre-treatment and industrial water reuse applications.

Conventional Treatment Limitations

Standard coagulation-flocculation-sedimentation — the backbone of most municipal water treatment — removes approximately 70–80% of microplastics by mass but is ineffective against smaller particles and nanoplastics. Activated carbon alone does not physically retain microplastics, though it can adsorb some plastic-associated chemical pollutants.

The CCL 6 Comment Period: What Stakeholders Should Do

EPA’s 60-day public comment period (ending June 2, 2026) is an opportunity for water utilities, industries, municipalities, and citizens to submit scientific data and technical comments to shape how microplastics are ultimately defined and regulated.

Key issues that remain unresolved and are open for public input:

• Case definition: What particle size range and polymer types will be regulated? Will nanoplastics be included?
• Analytical methods: No validated standardized method for microplastic quantification in drinking water exists yet — EPA must develop one before MCLs can be enforced
• Lab capacity: Certified laboratories capable of reliable microplastic analysis at ppb or ppt levels are limited nationally
• Treatment feasibility: Costs and technical requirements for large water systems to achieve very low microplastic concentrations need to be assessed

What Water Treatment Facilities Should Do Right Now

Even without binding MCLs for microplastics, proactive water quality managers should take these steps now:

1. Conduct baseline microplastic monitoring. Document current levels in source and finished water using available analytical methods. This data will be valuable for future regulatory compliance demonstrations.
2. Evaluate membrane treatment upgrades. Facilities currently using conventional treatment should assess the cost-benefit of adding UF or RO polishing stages. These investments address PFAS compliance simultaneously.
3. Review PFAS compliance status. The April 2027 PFAS compliance deadline is approaching. Membrane-based treatment planned for PFAS removal will also provide microplastic co-removal benefit.
4. Submit public comments to EPA. Water system operators have until June 2, 2026 to provide technical input on CCL 6. Practical operational feedback from the field is valuable to the rulemaking process.
5. Train operations staff. Keep staff informed on emerging regulatory developments. Early awareness enables planning for equipment procurement and budget allocation cycles.

AMPAC USA Water Treatment Solutions for Microplastic Removal

AMPAC USA, Manufactured in North America at our Woods Cross, Utah facility, designs and builds commercial reverse osmosis systems and industrial RO systems engineered for today’s most challenging water quality requirements — including PFAS, microplastics, nitrates, heavy metals, and dissolved solids.

Our membrane systems are designed to exceed current and anticipated regulatory standards, protecting municipalities, manufacturers, schools, hospitals, and commercial facilities from emerging contaminants before they become mandates.

Whether you need a 250 GPD commercial RO unit for a restaurant or a multi-million-gallon industrial system for a manufacturing facility, AMPAC USA engineers a solution matched to your flow rate, source water chemistry, and regulatory requirements.

Contact AMPAC USA today at (909) 762-8020 or visit our website to speak with a water treatment engineer about your microplastic removal and PFAS compliance needs.

Frequently Asked Questions About Microplastics in Drinking Water (2026)

Q: Does my tap water contain microplastics right now?

Likely yes, in small amounts. Studies have found microplastics in treated tap water across the United States and globally, though concentrations vary widely by source, treatment method, and pipe infrastructure age. The EPA CCL 6 listing means federal data collection on tap water levels will intensify in 2026-2027.

Q: Are microplastics regulated in drinking water today?

No. As of April 2026, there is no legally enforceable MCL for microplastics in U.S. drinking water. The EPA’s CCL 6 draft listing is a precursor to potential future regulation — the process typically takes 5-10 years from candidate listing to enforceable standard.

Q: Does boiling water remove microplastics?

No. Boiling water does not remove microplastics — it can actually increase their concentration as water volume reduces through evaporation. Physical filtration (reverse osmosis, nanofiltration, or ultrafiltration) is required to remove particles.

Q: Does a standard pitcher filter (like Brita) remove microplastics?

Activated carbon pitcher filters are not designed or certified for microplastic removal. Their pore sizes are far too large to reliably capture plastic particles. For effective microplastic reduction, NSF-certified reverse osmosis or ultrafiltration systems are the recommended options.

Q: When will the EPA set a legal limit (MCL) for microplastics?

There is no set timeline. EPA must first finalize CCL 6 (expected November 2026), then conduct regulatory determinations (typically 2-3 years), develop analytical methods, and complete cost-benefit analysis before proposing an MCL. Realistically, a proposed MCL for microplastics is unlikely before 2030-2032. However, state-level standards may emerge earlier.

Q: Which reverse osmosis systems does AMPAC USA recommend for microplastic removal?

AMPAC USA’s full line of commercial RO systems and industrial RO systems use high-rejection TFC membranes that remove microplastics, PFAS, dissolved solids, and heavy metals simultaneously. For point-of-use protection at home, our residential under-sink RO systems provide effective microplastic removal. Call (909) 762-8020 for a system recommendation based on your water quality report.

Q: How is the EPA CCL 6 different from PFAS regulations?

PFAS already have enforceable MCLs (set in 2024, compliance by April 2027). Microplastics on CCL 6 are at an earlier stage — candidate listing, not yet regulated. Think of CCL 6 as the starting gun, while PFAS is already in the final sprint toward compliance.