Brand Test · April 17, 2026
Does SmartWater have microplastics?
Yes — the bottle we tested did. It had been sitting in the back of a car for roughly a year. Hot days, cold nights, sunlight, compression. All the things that accelerate PET shedding. The filter came back so loaded it was hard to count individual dots.
The filter from a 1-year-old SmartWater bottle under blue light. Every pink dot is a particle consistent with plastic under Nile Red staining.
What SmartWater is
SmartWater is Coca-Cola's premium bottled water brand. The water is vapor distilled (an evaporation-condensation process that produces very pure water) and then mineralized with added electrolytes. It's sold in PET bottles — the same material used for Dasani, Aquafina, Fiji, and most of the bottled water market.
Distillation genuinely does produce clean source water. Then it goes into a PET bottle, the bottle ships across the country, the bottle sits on a shelf, the bottle sits in your car, and the bottle sheds plastic into the water the entire time.
Why the car matters
PET shedding is a function of temperature, UV exposure, and time. A car interior in summer can hit 140°F. That's not a controlled study condition — but it's the real condition for millions of people who keep cases of bottled water in their car for emergencies, road trips, or gym bags.
A 2020 University of Florida study found that room-temperature PET bottles stored for 16 weeks released measurably more microplastics than freshly-filled ones. Hot-car storage isn't in that study, but the direction is the same: more heat, more time, more shedding.
How to test your own bottle
Grab any bottle of SmartWater and run it through the microplastic test kit for bottled water. The kit uses separately sold tests. Do one on a fresh bottle. Do the second on a bottle you know has been sitting somewhere warm. The two filters next to each other will tell you everything you need to know. If you're comparing options first, see our roundup of the best microplastic test kits.
Common questions about SmartWater and microplastics
Does SmartWater have microplastics?
The bottle we tested did. SmartWater is vapor-distilled — clean at the source — but it ships and sits in a PET plastic bottle, the same material as Dasani, Aquafina, and Fiji, and PET sheds plastic into the water over time. The filter from a year-old bottle came back so dense with pink-glowing particles it was hard to count individual dots. No bottled-water brand is certified microplastic-free.
Is SmartWater safe to drink?
The water itself starts clean — vapor distillation removes essentially everything before minerals are added back. The concern isn't the source, it's the PET bottle: the longer it's stored and the warmer it gets, the more plastic it sheds into the water. Drink it fresh, keep it cool, and don't stockpile it in a hot car.
Does leaving SmartWater in a hot car increase microplastics?
Yes. PET shedding rises with temperature, UV exposure, and time, and a car interior in summer can hit 140°F. The bottle we tested had sat in a car for about a year and its filter came back heavily loaded. A 2020 University of Florida study found room-temperature PET bottles stored for 16 weeks released measurably more microplastics than freshly-filled ones — heat pushes the same effect further.
How can I test SmartWater for microplastics myself?
Run a before/after test at home. Filter one fresh bottle and one that's been sitting somewhere warm through an in-home microplastics kit (tests sold separately) and compare the two filter discs side by side. The kit detects microplastic particles down to about 1 µm; smaller nanoplastics need lab methods like py-GC/MS.
Takeaway
Premium source, long storage, and PET plastic do not combine well. If you buy bottled water, drink it fresh, keep it cool, and don't stockpile it in a hot environment. Or skip it entirely — a decent under-sink filter produces water that benchmarks cleaner than most premium bottled brands.
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