Microplastics in Sparkling Water: LaCroix, Bubly & Spindrift Ranked (2026)

Why carbonation changes the answer

Most of what you read about microplastics in bottled water is about still water, and the headline finding there is already substantial: a 2024 study using stimulated Raman scattering microscopy counted roughly 240,000 detectable plastic particles per litre in common bottled waters, the large majority of them nanoplastics small enough that earlier methods missed them entirely. That work was done on ordinary PET bottled water.

Carbonated water sits on top of that baseline with an extra mechanism. Dissolved CO₂ means the container is permanently pressurised from the inside. Separate research on plastic bottles has shown that mechanical stress, squeezing, shaking, repeated opening, and temperature cycling, measurably increases particle release from the bottle wall. Carbonation supplies that stress continuously rather than occasionally, and a warm bottle raises the internal pressure further.

This is why the usual advice to “just buy the big plastic bottle and decant” works less well for seltzer than for still water. It is also why the can-versus-bottle decision is worth more here than almost anywhere else in the drinks aisle.

The three formats, honestly

• Glass (best). No polymer in contact with the water at all. The cap liner is a tiny sealing surface and the only plastic in the system. This is the only format where the microplastics question essentially goes away.
• Aluminum can (good, with an asterisk). Aluminum cannot shed microplastics, so the PET problem disappears. But every food-grade can has a thin internal epoxy or acrylic liner to stop the metal reacting with the contents, and that liner is where bisphenol questions live. Most major brands have moved to BPA-NI (“non-intent”) liners, which means BPA is not deliberately used, not that the liner is inert. See are cans lined with plastic for the full picture.
• PET plastic bottle (worst). You get the still-water baseline plus the carbonation stress on top, plus whatever the bottle picked up from warehouse heat and shelf time. Large multi-serve PET bottles are the worst case because they are opened and resealed repeatedly, each cycle adding another pressure swing.

Sparkling water brands ranked by packaging

The pattern is unmistakable and it has nothing to do with brand quality or price: the flavour house you prefer barely matters, the container decides your exposure. A budget can beats a premium PET bottle on this measure every time.

The home-carbonation option

If you drink sparkling water daily, carbonating filtered water at home is the single biggest reduction available, because it removes both the warehouse heat and the shelf time. Two caveats worth knowing:

• Choose the glass carafe. Most home carbonators ship with a reusable PET bottle by default, and a reusable pressurised PET bottle that gets washed, refilled and re-pressurised hundreds of times is exactly the mechanical-stress scenario the research describes. Glass carafe versions are widely available.
• Filter first. Carbonating tap water carbonates whatever is already in it. A filter that is actually rated for particle reduction does the useful work here, see water filters compared.

Practical rules that actually move the number

• Glass first, can second, PET last. That ordering holds across every brand.
• Never store it warm. Heat raises both plastic shedding and internal pressure. A case in a hot garage, car boot, or sunny porch is the worst thing you can do to it.
• Skip the big resealable PET bottles. Repeated opening and resealing means repeated pressure cycling on the same wall.
• Don't freeze or shake PET. Both are mechanical stress, and a shaken carbonated bottle is under far more load than a still one.
• If you buy cans, that is a genuinely good choice, just know you have swapped a shedding question for a liner question rather than eliminating both.

Related: bottled water brands ranked, are cans lined with plastic, does Liquid Death have microplastics, and water left in a hot car.