Does bottled water have fewer microplastics than tap water?

What's actually in it

Tap water picks up microplastics from water treatment facilities, distribution pipes, and household plumbing. Bottled water starts the same way but then sits inside a plastic bottle, often in a warehouse or truck. That plastic bottle is itself a source of contamination.

Polystyrene, PET (the plastic in most water bottles), and polyethylene all shed particles over time, especially when exposed to heat or physical stress like squeezing. Bottled water also goes through more processing steps, each of which can add particles.

What the research says

A 2026 study in Sci Total Environ directly compared micro- and nanoplastic concentrations in treated tap water and commercially bottled water. Bottled water had higher particle counts in most comparisons, with a larger proportion of nanoplastics too small to filter or see.

The plastic bottle itself was identified as a direct source. PET particles matching the bottle's polymer signature appeared in the water. Bottles stored at higher temperatures leached more particles.

Tap water quality varies by location, and some municipal water contains higher plastic counts than others. But switching to bottled water doesn't reliably solve the problem and may make it worse.

A glass water pitcher with a carbon filter, or a stainless steel bottle filled from filtered tap water, exposes you to fewer plastics than either tap or bottled options from plastic containers.