Does Boxed Water have microplastics?
The short answer
Less than a plastic bottle, more than glass. The carton is mostly paperboard by weight, but a thin polyethylene film is what actually touches the water — and cartons measured around 11 particles per litre in the one format-comparison study.
Why Boxed Water scores 39
Polyethylene inner film in direct contact with the water for the whole shelf life
Cut edges and side seams where the laminate is exposed to the contents
A polyethylene screw cap, which is the same closure-abrasion story as a bottle
Fully opaque, so no UV pathway
Where the 39 comes from
Five components, added. The page renders the parts rather than a stored total, so the number cannot disagree with the reasoning behind it.
- Packaging contact
- 16 / 30
- Use conditions
- 6 / 25
- Measured release
- 8 / 25
- Polymer behaviour
- 6 / 10
- Processing
- 3 / 10
What material touches the contents, over how much surface area, for how long. Glass and steel score near zero here; a film pressed against fatty food scores near the top.
Heat, abrasion, flexing, repeated opening, reuse beyond design life. The same bottle scores differently in a fridge and in a hot car.
What a laboratory actually counted, for this product or its category. A high number here means real particles were measured, not that the material looks suspicious.
How this specific polymer behaves — brittleness, fat solubility of its additives, thermal stability, whether it is a polymer named in existing restrictions.
What happened before you bought it. Retort sterilisation inside the pack, hot-filling, and pressurised brewing all happen at the most migration-favourable moment.
What we don't know
Cartons as a category measured well in Schymanski 2018 — 11 particles per litre, the lowest of the four formats it compared. But that study used a method blind to sub-micron particles, and a polyethylene film is exactly the kind of surface later nanoplastic work has found to be productive. The category number is likely a floor.
This section is on every page in the database, including the ones where the answer is comfortable. How evidence grades work →
Better options
Ordered by how much they change, not by how much they cost.
Check the one in your hand
This page scores Boxed Water as a product. Formulations, packaging and suppliers change, and the specific item you own has its own condition — a scratched pan and a new one are not the same object. Scan yours for a score built from what is actually in front of you.
Scan my drinking waterSources behind this score
Each with the finding we use it for and the limitation that finding carries — because a study quoted without its boundaries is how this subject got so noisy.
- peer-reviewed2018
Schymanski 2018 — Compared formats head to head: single-use PET averaged 14 particles/L, returnable PET 118/L, glass bottles 50/L and beverage cartons 11/L.
Limitation: The glass result is the one people skip. Glass was not zero — particles came from the cap and the filling line, not the bottle wall. Small sample per format.
- report2026
Earth Action 2026 — Estimated roughly 1,000 tonnes of microplastics migrate from packaging into food and drink annually — about 130 mg per person per year — with PET bottles responsible for around a third, and found UV exposure can raise release up to 100×.
Limitation: An industry-funded modelling exercise, not a laboratory study, and not peer-reviewed. We use it for the relative ranking of formats rather than for any absolute number.
- peer-reviewed2022
Zangmeister 2022 (NIST) — Nylon bags, LDPE food-storage bags and similar single-use plastics shed trillions of sub-100 nm particles per litre in ordinary contact with water.
Limitation: Deionised water at controlled temperature. Nanoparticle counts are inherently large numbers; the study is about their existence and quantity, not their fate in the body.