Stainless steel or plastic: what we'd choose for school

Think about an average week: the bottle rolls through a backpack with books and a lunchbox, stands in the sun during break and is cleaned with a brush or in the dishwasher. That's a lot of wear for something your child drinks from every day.

Plastic is light and cheap, but it scratches more easily. Over time those small scratches can hold on to smells and a slight aftertaste, especially with juice or milk. Many parents recognise the moment a bottle simply doesn't smell fresh anymore.

In 2020, researchers at Trinity College Dublin tested plastic baby bottles made of polypropylene. When the bottles were sterilised and used with hot water, as you would when preparing formula, they released microplastic particles. The hotter the water, the more particles they found.

What this means for health isn't clear yet; scientists are still studying it. But it's a good reason not to put hot drinks in plastic, and to replace plastic bottles once they're scratched or cloudy.

• It lasts. Steel doesn't crack when it's dropped and doesn't scratch the way plastic does.
• No aftertaste. Steel doesn't take on smells or flavours, so water keeps tasting like water.
• Easy to clean. The bottle can go in the dishwasher.
• Warm or cold. The double wall keeps drinks at temperature for longer.

The drink sits in stainless steel. The lids and straws of our bottle do contain plastic parts, which are BPA-free. Our advice: replace a straw when it looks worn, and let hot drinks cool down before they go in.