Is it safe to mix formula with hot tap water from a plastic kettle?
No. Plastic kettles shed microplastics when heated, and chlorinated tap water makes the mix worse.
What's actually in it
Plastic electric kettles are usually polypropylene. Boiling water inside a plastic kettle releases microplastics, nanoplastics, and antioxidant additives. If your tap water is chlorinated, those chlorine byproducts meet the plastic particles in the same pot.
Formula mixed with this water goes straight into a baby.
What the research says
A 2025 study in Food Chem tested cell responses to plastic particles plus chlorination byproducts. The combined mix was more toxic than either alone. A 2025 study showed polypropylene containers shed billions of nanoplastics in hot water.
Use a glass or stainless steel kettle. If your tap is heavily chlorinated, filter before boiling. Let boiled water cool in a glass pitcher below 70°C before mixing with formula.
The research at a glance
| Study | Journal | Year |
|---|---|---|
| Released micro/nano-plastics from plastic containers amplify toxicity of disinfection by-products. | Food Chem | 2025 |
| Release of Nanoplastics from Polypropylene Food Containers. | J Agric Food Chem | 2025 |
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