PFAS and Microplastics in Tap Water: What We Know and What You Can Do
Written By Kevin Wallace.
PFAS, the forever chemicals, are estimated in at least 45 percent of U.S. tap water. Microplastics have been found in most tap samples that have been looked at, and in bottled water too. The health evidence is stronger for PFAS than for microplastics. For both, the useful response is to find out what is in your own water and filter it if the numbers call for it. Not to panic.
Water is the one thing every one of us consumes every day. Most people have never read their water quality report. Most of what circulates on social media about toxic tap water is either exaggerated or out of date.
This article covers what PFAS and microplastics are, how common they are, what the research actually links them to, where the regulations stand as of October 2026, and the practical steps worth taking. A companion article covers chlorine, chloramine, and disinfection byproducts.
1. What PFAS are, and what the evidence links them to
PFAS (per- and polyfluoroalkyl substances) are a family of thousands of synthetic chemicals used since the 1940s in nonstick cookware, stain- and water-resistant fabrics, food packaging, and firefighting foam. The carbon-fluorine bond that makes them useful also makes them nearly indestructible. They build up in the environment and in our bodies, which is why they are called forever chemicals.
In 2022 the National Academies of Sciences, Engineering, and Medicine reviewed the evidence. They found sufficient evidence of an association between PFAS exposure and four effects (1):
Decreased antibody response to vaccines, in adults and children
Dyslipidemia (elevated cholesterol), in adults and children
Decreased infant and fetal growth
Kidney cancer in adults
A second tier, limited or suggestive evidence, covers testicular cancer, breast cancer, ulcerative colitis, thyroid disease, and pregnancy-induced hypertension. Those are not in the sufficient list. They are why some of them still appear in the follow-up table.
The same report gave clinicians a framework based on the sum of seven PFAS in serum or plasma (1):
| Blood level (sum of 7 PFAS) | What the report says | Recommended follow-up |
|---|---|---|
| Below 2 ng/mL | Adverse effects are not expected at this level, on current evidence | None specific to PFAS |
| 2–20 ng/mL | Potential for adverse effects, especially in sensitive groups such as pregnancy | Reduce exposure. Screen for dyslipidemia. In pregnancy, screen for hypertensive disorders. Screen for breast cancer by age and other risk factors. |
| Above 20 ng/mL | Higher risk of adverse effects | All of the above, plus thyroid testing, and assessment for kidney cancer, testicular cancer, and ulcerative colitis at wellness visits |
Testing is recommended mainly for people with higher-than-average exposure: firefighters and other occupational exposures, and people who have lived in documented contamination areas or near facilities that used fluorochemicals, military bases, commercial airports, landfills, incinerators, wastewater plants, or farms where sewage sludge was applied (1).
2. How common PFAS are in tap water
The best national snapshot of kitchen taps, wells and public supplies together, is still the U.S. Geological Survey study led by Kelly Smalling. Researchers tested tap water at 716 locations, 269 private wells and 447 public supplies, collected from 2016 to 2021, for 32 PFAS compounds. They estimated that at least one PFAS could be detected in about 45 percent of U.S. tap water (2).
Three findings stand out.
Private wells were not safer. Profiles and estimated median cumulative concentrations were similar in private wells and public supplies. That matters for rural families who assume well water is automatically clean.
Location matters. Detections were more likely in urban areas and near known PFAS sources. The USGS map highlights the Great Lakes region, the Eastern Seaboard, the Great Plains, and central and southern California.
The most frequently detected compounds were PFBS, PFHxS, and PFOA, each in about 15 percent of samples. “Most frequent” is not “in most water.”
A newer public-system dataset is EPA’s Fifth Unregulated Contaminant Monitoring Rule, UCMR 5, collected 2023–2025 and released in final form in August 2026. It covers 29 PFAS plus lithium in community systems, not private wells. Read it next to your Consumer Confidence Report. The 45 percent figure is a national estimate from a few hundred taps. Your own tap can be far better or far worse (3).
Tap water is only one route. For many people food is larger: fish, grease-proof packaging, and nonstick cookware. Treated carpets, stain-repellent clothing, and house dust add more. Biosolids are the rural route people miss. Sewage sludge applied to fields can carry PFAS into soil and, from there, into a well that has no factory nearby. Water is simply the route most of us can do the most about. Showering and laundry are minor routes by comparison. A drinking-water filter solves a drinking-water problem.
3. Where the regulations stand
The rules have been changing. This is where they stand as of October 2026.
| Standard | PFOA | PFOS | Other PFAS | Status |
|---|---|---|---|---|
| EPA rule, finalized April 10, 2024 | 4 ppt | 4 ppt | MCLs for PFHxS, PFNA, and GenX (HFPO-DA), plus a hazard index for mixtures with PFBS | Compliance date April 26, 2029 |
| EPA proposal, May 18, 2026, deadline docket | 4 ppt kept | 4 ppt kept | Does not change the other limits | Comment period closed July 20, 2026. Would let systems request an extension to April 26, 2031. Not final. |
| EPA proposal, May 18, 2026, rescission docket | 4 ppt kept | 4 ppt kept | Proposes to rescind PFHxS, PFNA, GenX, and the hazard index | Separate proposal. Comment period also closed July 20, 2026. Not final. |
| New York State, adopted 2020 | 10 ppt | 10 ppt | Also 1 ppb for 1,4-dioxane, which is not a PFAS. New York was first to set that state limit. | In force now for public systems. Weaker than the federal 4 ppt, and the number systems must meet until the federal date. |
One part per trillion is about one drop in 20 Olympic swimming pools. These are extraordinarily low limits, which reflects how potent and persistent these chemicals are.
Two practical points follow. The federal 4 ppt limits for PFOA and PFOS have survived both 2026 proposals. The other four limits may go away if the rescission proposal is finalized. Public systems in New York must already monitor for PFOA and PFOS and act above 10 ppt (4). Private wells are not covered by any of these rules. Well owners test their own water.
4. Microplastics: in the water, and in us
Microplastics are plastic fragments smaller than 5 millimeters. Nanoplastics are smaller still, below one micrometer, small enough that some can cross cell membranes. They come from breaking-down packaging, synthetic clothing fibers, tire dust, and industrial processes.
In tap water. A 2017 investigation commissioned by Orb Media found plastic fibers in 83 percent of tap water samples worldwide and 94 percent of U.S. samples (5). It was journalism-led rather than peer-reviewed. Later academic work has confirmed that microplastics are widespread in treated water. “Nearly all of it” is a fair description of the samples that have been tested. It is not a census of every tap.
In bottled water. Bottled water is not the escape many people assume. Using a laser-imaging method, Columbia University researchers found an average of about 240,000 plastic particles per liter in three popular U.S. brands, about 90 percent of them nanoplastics, with a range of about 110,000 to 370,000 (6). They expected most of it to be PET from the bottles. They found several plastics. The PET particles were the larger ones. The brands were not named.
In the human body. Two studies drew wide attention.
| Study | What was found | Key limitation |
|---|---|---|
| Marfella et al., New England Journal of Medicine, 2024 | Polyethylene in 150 of 257 carotid plaques (58.4%). Over a mean 33.7 months, those patients had a hazard ratio of 4.53 for heart attack, stroke, or death. | Observational. Patients already needed plaque surgery. Pyrolysis methods in this field can misread lipids as plastic. |
| Nihart et al., Nature Medicine, 2025 | Plastic particles in decedent brain, higher in 2024 samples than 2016, and higher still in dementia brains. | Authors assume no causality: dementia already means atrophy and a leakier barrier. Reviewers, including Germany’s BfR, call the amounts implausibly high. Duplicated supplementary images were confirmed. Methods are contested. |
The official view is still cautious. In 2019 the World Health Organization rated the health risk from microplastics in drinking water as low on the evidence then available. Particles larger than about 150 micrometers are unlikely to be absorbed. Wastewater treatment can remove over 90 percent of microplastics, and conventional drinking-water treatment removes many of the rest (9). WHO also said the evidence was limited, especially for the smallest particles. That report predates the studies above.
The honest summary: microplastics are widespread, including in tissues, and the early human associations are concerning. We do not yet know how much harm they cause, or at what level. The brain concentrations in particular should not be repeated as settled fact.
5. What you can do
Read your water quality report. Every community water system must publish an annual Consumer Confidence Report. Find yours through EPA’s lookup tool or by asking your utility (10). Compare PFAS results with the table above, and check UCMR 5 if your system was monitored (3).
If you have a private well, test it. Nobody else will. Your county health department can point you to a certified lab. Ask for PFAS, not a general potability panel. If the land around you has taken sewage sludge, say so when you order the test (4).
Do not boil water to remove PFAS. Boiling does not destroy them, and it concentrates them as water evaporates.
Boiling can help with microplastics in hard water, if you then filter the scale. In a 2024 study of spiked tap water from Guangzhou, boiling removed up to 90 percent of free-floating micro- and nanoplastics in hard water (300 mg/L as calcium carbonate) and about 25 percent in soft water. The particles were trapped in limescale. The authors suggest pouring the cooled water through a coffee filter to catch that scale (12). Central New York water is often hard, so the higher number is the relevant one. This was not a U.S. utility trial, and it does nothing for PFAS.
Filter if your water needs it. Look for NSF/ANSI 53 or NSF/ANSI 58 certification specifically for PFOA and PFOS reduction, not a generic NSF mark. Reverse osmosis, standard 58, is the broad tool and also cuts microplastics. Activated carbon, standard 53, works better on long-chain compounds than on short-chain PFBS, which was one of the compounds USGS found most often. Change the cartridge on schedule. A spent filter stops working and can release what it caught.
Do not switch to bottled water for this reason. The nanoplastic load, the cost, and the plastic waste make it a poor everyday fix, except as a short-term measure when your water exceeds a limit (6).
Reduce the other easy sources. Replace scratched nonstick pans with stainless steel or cast iron, avoid heating food in plastic, and skip stain-repellent treatments on carpets and clothing.
For people with high exposure, such as firefighters, one randomized trial found that regular plasma donation lowered mean serum PFOS by 2.9 ng/mL over a year, and blood donation lowered it by 1.1 ng/mL. Observation did not change the level (13). Whether that improves health is not yet known. It is not a reason for an ordinary household to start donating plasma.
6. Honest caveats
Detection is not the same as harm. Instruments can find almost anything at parts per trillion. The question is dose. For many PFAS, and for microplastics, we do not yet know a safe dose.
The microplastics studies are early. The heart finding is an association in people who already had carotid plaque. The brain finding is contested on method and on the size of the numbers. They justify caution and better measurement, not certainty.
The 45 percent figure is an estimate from 716 sites, 2016–2021. UCMR 5 is newer, and it covers public systems only. Only a local test tells you about your tap.
Regulations are in flux. Both May 2026 proposals closed their comment periods on July 20, 2026. Neither is final. Check EPA’s PFAS drinking-water pages before you treat a headline as the rule.
This is not medical advice. I am a veterinarian and a board-certified internist. I am not your physician. If you have high exposure, talk with your doctor about the National Academies testing guidance.
7. Where we land
This is what taking responsibility for our own health looks like in practice. It is not fear, and it is not blind trust. It is getting the facts about your own water and acting on them.
PFAS are the better-established concern. The evidence ties them to real health effects, regulators have put PFOA and PFOS at 4 ppt, and certified home filters exist. Microplastics are the less certain concern. They are worth reducing where it is easy, because they are showing up in places no one wants them. Bottled water is not the way to do that.
Know your water. Read your Consumer Confidence Report, or test your well.
Filter when the numbers call for it, with a filter certified to NSF/ANSI 53 or 58 for PFOA and PFOS reduction. Reverse osmosis is the one that handles PFAS and microplastics together.
Skip bottled water as an everyday solution.
Cut the easy sources: worn nonstick pans, food heated in plastic, stain-repellent treatments, and, on a farm, sludge-treated fields uphill of a well.
Stay with primary sources: your utility, your state health department, UCMR 5, and EPA. Not a social-media headline.
The companion piece on this site is chlorine, chloramine, and the byproducts disinfection leaves behind. A filter comparison will come later. It is not up yet.
8. Further reading
If you open two, open the National Academies report and the USGS tap-water paper.
9. On our website
Chlorine, Chloramine, and Disinfection Byproducts What treatment plants add on purpose, and what those additives leave behind.
10. References
National Academies of Sciences, Engineering, and Medicine. Guidance on PFAS Exposure, Testing, and Clinical Follow-Up. Washington, DC: National Academies Press; 2022. doi:10.17226/26156. https://nap.nationalacademies.org/catalog/26156/guidance-on-pfas-exposure-testing-and-clinical-follow-up
Smalling KL, Romanok KM, Bradley PM, et al. Per- and polyfluoroalkyl substances (PFAS) in United States tapwater: comparison of underserved private-well and public-supply exposures and associated health implications. Environ Int. 2023;178:108033. https://doi.org/10.1016/j.envint.2023.108033
U.S. Environmental Protection Agency. Fifth Unregulated Contaminant Monitoring Rule data finder. Final dataset released August 2026. https://www.epa.gov/dwucmr/fifth-unregulated-contaminant-monitoring-rule-data-finder
New York State Department of Health. Public water systems and drinking water standards for PFAS and other emerging contaminants. https://www.health.ny.gov/environmental/water/drinking/emerging_pfas_publicwater.htm
Kosuth M, Mason SA, Wattenberg EV. Anthropogenic contamination of tap water, beer, and sea salt. The Orb Media tap-water investigation was reported in Time, September 6, 2017. https://time.com/4928759/plastic-fiber-tap-water-study/
Qian N, Gao X, Lang X, et al. Rapid single-particle chemical imaging of nanoplastics by SRS microscopy. Proc Natl Acad Sci U S A. 2024;121(3):e2300582121. Summary: https://www.publichealth.columbia.edu/news/bottled-water-can-contain-hundreds-thousands-nanoplastics
Marfella R, Prattichizzo F, Sardu C, et al. Microplastics and nanoplastics in atheromas and cardiovascular events. N Engl J Med. 2024;390(10):900-910. https://www.nejm.org/doi/full/10.1056/NEJMoa2309822
Nihart AJ, Garcia MA, El Hayek E, et al. Bioaccumulation of microplastics in decedent human brains. Nat Med. 2025;31(4):1114-1119. https://www.nature.com/articles/s41591-024-03453-1
World Health Organization. Microplastics in drinking-water. Geneva: WHO; 2019. https://www.who.int/publications/i/item/9789241516198
U.S. Environmental Protection Agency. Consumer Confidence Reports. https://www.epa.gov/ccr
U.S. Environmental Protection Agency. Extending the compliance deadline for the PFOA and PFOS maximum contaminant levels. Proposed rule. Fed Regist. May 20, 2026. Docket EPA-HQ-OW-2025-1742. Comment period closed July 20, 2026. https://www.epa.gov/sdwa/proposed-pfoa-and-pfos-compliance-extension-rule
Yu Z, Wang JJ, Liu LY, Li Z, Zeng EY. Drinking boiled tap water reduces human intake of nanoplastics and microplastics. Environ Sci Technol Lett. 2024;11(3):273-279. ACS summary: https://www.acs.org/pressroom/presspacs/2024/february/want-fewer-microplastics-in-your-tap-water-try-boiling-it-first.html
Gasiorowski R, Forbes MK, Silver G, et al. Effect of plasma and blood donations on levels of perfluoroalkyl and polyfluoroalkyl substances in firefighters in Australia: a randomized clinical trial. JAMA Netw Open. 2022;5(4):e226257. https://pubmed.ncbi.nlm.nih.gov/35394514/
U.S. Environmental Protection Agency. Proposed PFAS rescission rule, PFHxS, PFNA, HFPO-DA, and the hazard index. Docket EPA-HQ-OW-2025-0654. Comment period closed July 20, 2026. https://www.epa.gov/sdwa/proposed-pfas-rescission-rule
