Reverse osmosis removes the most. Its membrane pores are roughly 0.0001 micron, tight enough to block microplastics and the far smaller nanoplastics that every pitcher misses. A certified membrane pitcher is the practical middle: a filter independently certified or lab-tested to NSF/ANSI 401 (Brita Elite, Clearly Filtered) strains most microplastics down to about half a micron with no plumbing. A carbon-only pitcher is the weakest pick. In controlled testing, one such device shed particles and left more plastic in the water than it removed.
The Great Lakes supply drinking water to about 40 million people, and some microplastic makes it through to the tap. Boiling hard water before you filter it knocks the count down further, for free.
What the research shows about microplastics in Great Lakes tap water
Two studies matter here, and they measured different things.
The tap-water evidence comes from a 2018 PLOS ONE study by Kosuth, Mason, and Wattenberg, which tested 159 samples from 14 countries. It found microplastics in 81% of them, averaging 5.45 particles per liter, and 98% of those particles were fibers. North America was the worst region tested. U.S. tap water came back positive 94% of the time and averaged 9.24 particles per liter, well above the global mean. The study sampled U.S. taps broadly, Great Lakes communities included, so that number applies here.
The second study describes the water before it reaches your treatment plant. A 2016 study in Environmental Science & Technology by Baldwin, Corsi, and Mason (the lead author is a USGS scientist) sampled 29 tributaries that drain into the Great Lakes across six states. Plastic showed up in every one of the 107 samples. Fibers and lines made up about 71% of what they found, with fragments around 17%. The fragment, film, and pellet loads tracked with urban land cover and wastewater, while fibers turned up everywhere regardless. That's the plastic flowing down the rivers toward the intakes your city draws from.
The rivers run dirty, treatment catches most of it, and what reaches the tap is still the most plastic-heavy of any region measured. Treatment strips out the bulk. Your filter handles the last stretch, the particles small enough to slip through sand filtration.
Best water filter for Great Lakes tap water: Brita Elite vs. Clearly Filtered vs. reverse osmosis
If a basic carbon pitcher won't cut it, three tiers are worth knowing, from a cheap certified pitcher up to full reverse osmosis (an under-sink system that forces water through an ultra-fine membrane). The table compares them on how small a particle each one actually stops, plus price, install effort, and what else they remove. Two things as you read it. A smaller micron number means a tighter filter, so lower is better. And the pitcher certifications stop at about half a micron, which is the part the marketing skips. If you already own a carbon pitcher and want the detail on where its certification begins and ends, our guide to whether Brita filters microplastics walks through the NSF/ANSI 401 testing itself.
| Brita Elite (pitcher) | Clearly Filtered (pitcher) | iSpring RCC7 (reverse osmosis) | |
|---|---|---|---|
| How it filters | Dense carbon block + ion exchange | Multi-stage proprietary "Affinity" media | Semipermeable RO membrane (~0.0001 µm pores; pressure pushes water through openings so tiny almost nothing else fits) |
| Microplastics | Certified to NSF/ANSI 401 (≥85%, down to ~0.5 µm) | Independently lab-tested to NSF/ANSI 401 among 365+ contaminants | Near-complete rejection in membrane reviews |
| Nanoplastics (<0.5 µm) | Not covered by certification | Not specifically certified | Yes. Pores exclude particles below 100 nm |
| The half-micron caveat | NSF/ANSI 401 only tests down to ~0.5 µm. Below that, a certified pitcher and an uncertified one are equally unproven. | Filters below the certification floor entirely, the only tier that addresses nanoplastics. | |
| Also removes | Lead, chlorine, some metals (NSF 42/53) | PFAS, lead, fluoride, many more (per company testing) | Dissolved salts, PFAS, most everything |
| Format & effort | Countertop pitcher, no install | Countertop pitcher, no install | Under-sink, plumbing install, wastes some water |
| Best for | Entry point | Step up | Maximum removal |
| Shop | Brita Elite Filter → | Clearly Filtered Pitcher → | iSpring RCC7 RO System → |
For the cheapest real improvement over a basic pitcher, start with the Brita Elite, the most affordable filter that actually carries a microplastics certification. The Clearly Filtered pitcher is the step up if you also want documented PFAS and heavy-metal reduction without leaving the pitcher format. For the most complete removal, including the nanoplastics and dissolved contaminants no pitcher touches, a reverse osmosis system like the iSpring RCC7 is as far as household treatment goes. Whichever you pick, avoid a plain carbon-and-resin pitcher: a 2023 University of Toronto study in Polymers found a carbon-only device left more particles in the water than it started with.
Great Lakes tap water by city
Every city below draws treated water straight from a Great Lake or a connecting bay, so the source-water findings above apply to all of them. Great Lakes water is generally hard, often near or above the mineral level where boiling works best, so across most of the basin, boiling before you filter is a real first step. Confirm your own hardness on your city's annual water quality report before you buy.
Traverse City, MI
Home base. Cold, mineral-rich Lake Michigan water that responds well to boiling first. A certified pitcher covers most households; reverse osmosis if you want the ceiling.
Grand Rapids, MI
Supplied from a Lake Michigan intake on the shoreline between Holland and Grand Haven. Same hard-water profile as the rest of the Michigan coast. Boil, then filter with a 401-certified pitcher or RO.
Milwaukee, WI
Two Lake Michigan treatment plants serve the metro. Well-run utility, but treatment doesn't target sub-micron plastic, so a certified membrane pitcher is the sensible add-on.
Chicago, IL
One of the largest surface-water systems in the world, all Lake Michigan. Volume doesn't change the particle math. For nanoplastics, only reverse osmosis clears the certification floor.
Cleveland, OH
Drawn from Lake Erie, the shallowest, warmest, and most plastic-burdened Great Lake in surface surveys. A strong case for RO if the budget allows.
Detroit, MI
The Great Lakes Water Authority draws from Lake Huron and the Detroit River to supply Detroit and dozens of southeast Michigan communities. Hard water, so boil-then-filter helps; a certified pitcher or RO handles the rest.
City source and hardness details are generalized from public utility information and can change year to year.
The free first step: boil, then filter
Before you spend anything, there's a nearly free move that works on hard water, which most of the Great Lakes basin has. A 2024 study in Environmental Science & Technology Letters found that boiling hard tap water removed up to about 90% of nano- and microplastics. As the water heats, calcium carbonate (limescale, the crust in your kettle) crystallizes and traps the plastic inside it. Pour the cooled water through a basic filter or fine strainer to catch that crust, and the plastics leave with it. Hardness matters. Soft water saw only about 25% removal, but Great Lakes water runs mineral-rich, so the trick works here. Boil, filter, then let a certified pitcher or RO handle the rest.
Frequently Asked Questions
Is there microplastic in Great Lakes tap water?
Almost certainly some. The 2018 PLOS ONE tap-water study by Kosuth, Mason, and Wattenberg found microplastics in 81% of tap water sampled worldwide, and North American tap water was the most contaminated of any region, with 94% of U.S. samples coming back positive, averaging 9.24 particles per liter. A 2016 Environmental Science & Technology study by Baldwin, Corsi, and Mason found plastic in all 107 samples from 29 tributaries feeding the lakes, which is the source water heading toward treatment plants. Municipal treatment removes most of it; a point-of-use filter handles what's left. (Kosuth et al., 2018, PLOS ONE; Baldwin et al., 2016, ES&T)
What is the best water filter for Great Lakes tap water?
Reverse osmosis removes the widest range. Its membrane pores are roughly 0.0001 micron, small enough to exclude both microplastics and nanoplastics, and peer-reviewed membrane reviews report near-complete rejection. For most households the practical middle option is a pitcher with a microfiltration membrane certified or independently lab-tested to NSF/ANSI 401, such as the Brita Elite or Clearly Filtered. (Membrane technologies review, Water Science & Technology, 2023)
Do basic carbon pitchers remove microplastics from Great Lakes tap water?
Not reliably. A carbon-and-ion-exchange pitcher is built to adsorb chlorine, taste, and some metals, not to physically strain sub-micron plastic. In a 2023 University of Toronto study in Polymers, a device using only granular activated carbon and ion exchange put more particles into its filtered water than the tap water contained, while devices with a physical microfiltration membrane removed 78 to 100% of microplastic fragments. Look for an NSF/ANSI 401 certification, or step up to reverse osmosis. (Cherian et al., 2023, Polymers)
Is Great Lakes tap water hard enough that boiling helps?
Usually. Great Lakes surface water is generally moderately hard, often near or above the ~120 mg/L of calcium carbonate where boiling works best. A 2024 study in Environmental Science & Technology Letters found boiling hard tap water removed up to about 90% of nano- and microplastics as they get trapped in the limescale that forms, which you then filter out. It's a cheap first step, not a replacement for a filter. Confirm your hardness on your city's water quality report. (Yu et al., 2024, Environ. Sci. Technol. Lett.)
Does reverse osmosis remove nanoplastics from Great Lakes water?
Yes, and it's the only common household method that does. Reverse osmosis pores are about 0.0001 micron, excluding particles below 100 nanometers, the nanoplastic size class every pitcher certification misses. NSF/ANSI 401 pitchers are only tested down to about half a micron, so if the smallest particles are your concern, an under-sink RO system is the household ceiling. (Membrane technologies review, Water Science & Technology, 2023)
Sources & further reading
- Kosuth, M., Mason, S. A., & Wattenberg, E. H. (2018). Anthropogenic contamination of tap water, beer, and sea salt. PLOS ONE, 13(4), e0194970. plos.org
- Baldwin, A. K., Corsi, S. R., & Mason, S. A. (2016). Plastic Debris in 29 Great Lakes Tributaries: Relations to Watershed Attributes and Hydrology. Environmental Science & Technology, 50(19), 10377–10385. pubs.acs.org
- Cherian, A. G., Liu, Z., McKie, M. J., Almuhtaram, H., & Andrews, R. C. (2023). Microplastic Removal from Drinking Water Using Point-of-Use Devices. Polymers, 15(6), 1331. mdpi.com
- A review of microplastic removal from water and wastewater by membrane technologies (2023). Water Science & Technology, 88(1), 199–260. iwaponline.com
- NSF/ANSI 401 reduction protocol — Update on Microplastics Reduction Claims (2022). Water Conditioning & Purification International. wcponline.com
- Yu, Z., Wang, J.-J., Liu, L.-Y., Li, Z., & Zeng, E. Y. (2024). Drinking Boiled Tap Water Reduces Human Intake of Nanoplastics and Microplastics. Environmental Science & Technology Letters, 11(3), 273–279. pubs.acs.org
For educational purposes only — not medical advice. MicroClarity reports peer-reviewed research; it does not diagnose or treat.