Research · May 26, 2026
Does my tap water have microplastics?
On the largest published tap-water survey to date, the answer is yes in 94% of US homes. That doesn't mean your specific tap is dirty, and it doesn't tell you how many. It means the base rate is unforgiving and the only way to get a number you can act on is to run the test on your own water.
What the published surveys say
Four studies do most of the work in this conversation:
| Study | Sample | Finding | Count |
|---|---|---|---|
| Orb Media / University of Minnesota (2017) | 159 tap samples, 14 countries | 83% global, 94% US contained microplastic fibers (>100 µm) | ~5 fibers per 500 mL in US samples |
| Mason et al. / SUNY Fredonia (2018) | 259 bottled-water samples, 11 brands | 93% contained microplastic particles | ~325 particles per liter average, ~10,000 max |
| Pivokonsky et al. / Czech Republic (2018) | Three water treatment plants, raw and treated | Detected in 100% of treated drinking water samples | 338–628 particles per liter (treated) |
| Qian et al. / Columbia + Rutgers, PNAS (2024) | Bottled water, three US brands | Down to 100 nm resolution; ~90% nanoplastic | ~240,000 particles per liter |
Two patterns hold across every dataset. First, the population-level answer is “almost always yes.” Second, the particle count depends heavily on what you can actually see. Studies that only count above 100 µm get small numbers. Studies that push resolution into the nanoplastic range get numbers that are 1000x bigger from the same glass of water.
Where does the plastic come from
Three sources, in roughly increasing contribution: the raw water source itself (rivers, reservoirs, groundwater all carry some background plastic load from runoff and atmospheric deposition), the treatment plant (conventional coagulation/flocculation removes some particulate but not all), and the distribution and indoor plumbing path (PEX, PVC, polypropylene, and rubber gaskets shed particles, especially after disturbance).
The Czech study by Pivokonsky and colleagues measured raw and treated water at three different plants and found treatment reduced but did not eliminate microplastic load. Particles got smaller on average after treatment, which is consistent with floc removing large pieces while small ones slip through.
A 2019 review in Water Research concluded that the contribution from plastic distribution pipes can equal or exceed the contribution from the source water in homes with extensive plastic plumbing. If your house was built or repiped in the last 20 years, this is the likeliest single explanation for a high reading.
Does your utility test for it
No US utility is required to test for microplastics, and very few do voluntarily. The EPA added microplastics to Contaminant Candidate List 6 in April 2026 — the first step in a regulatory pipeline that historically takes 10–20 years to produce an enforceable Maximum Contaminant Level. California passed SB 1422 in 2018 requiring the state to define and monitor microplastics in drinking water; the resulting Policy Handbook from the State Water Resources Control Board went into effect in 2022 but monitoring is limited to large utilities and the results are not surfaced to customers in their annual reports.
Your Consumer Confidence Report — the annual water-quality document your utility mails or links to every July — does not contain microplastic data. You can read more about what utilities do and don't test for in the EPA CCL6 explainer.
High-likelihood homes
Some pipe and source configurations virtually guarantee detectable microplastics from the cold tap:
- Post-2005 new construction with PEX whole-home plumbing. Cross-linked polyethylene service lines and distribution lines shed measurable PE flakes, especially on the hot side.
- Recently repiped homes (any decade). A repipe within the last 10 years almost always means PEX or CPVC. Both shed.
- Homes with plastic-lined hot-water tanks. The dip tube on most tank heaters is plastic. Failing dip tubes are a documented source of large PE fragments at the hot tap.
- Homes on surface-water utilities (rivers, lakes, reservoirs). Surface-fed systems carry more background microplastic than groundwater-fed systems before treatment.
- Multi-family buildings with shared plastic risers. Older apartments and condos retrofitted with PEX risers concentrate the shedding effect.
The only way to get your number
Population statistics tell you whether there is plastic in your water. They don't tell you how much, which means they don't tell you whether your filter is working, whether your new repipe made the problem worse, or whether the bottled water you switched to is dirtier than the tap you stopped trusting. The only path to those answers is a measurement on your specific glass.
The protocol is straightforward: filter 100 mL through a 1 µm membrane, stain with Nile Red, photograph under 450nm blue light through an orange filter, count the pink dots. A university lab will run that for $200–$600. The kit on this site ($50, two tests, free shipping) ships the same chemistry in a form you can run on a kitchen table in 15 minutes. Step-by-step here: how to test water for microplastics at home.
Most people test three samples: their cold morning tap, their filter output, and whatever they were planning to switch to. That's enough to make a real decision about what you put in your body.
Related