Do PET plastic water bottles leach phthalates into the water?
Yes. Despite not being added intentionally, phthalates are found in PET plastic and migrate into water, especially when bottles are heated or stored for long periods.
What's actually in it
PET (polyethylene terephthalate) plastic, the clear plastic used in most disposable water bottles, is sometimes described as free from plasticizers like phthalates. But the manufacturing process and recycling can introduce phthalate contamination, and residual chemicals from the polymerization process can leach out.
Heat speeds migration significantly. A water bottle left in a hot car, sitting in direct sunlight, or filled with hot liquid releases far more chemicals than one kept cool and dark.
What the research says
A 2026 study on phthalate migration from PET bottles measured migration under different storage conditions and confirmed that phthalate compounds move from PET into water. Migration increased with temperature, UV exposure, and storage duration.
Even at room temperature over typical store shelf times, detectable phthalate levels appeared in the water. DEHP and DBP, both endocrine-disrupting phthalates, were among the compounds detected.
Glass and stainless steel water bottles don't have this problem. If you use plastic bottles, avoid leaving them in hot cars, never refill single-use bottles multiple times, and don't store water in plastic bottles for extended periods.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Migration of phthalate compounds from polyethylene terephthalate bottles under different storage conditions | Food Chem | 2026 |
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