Hey, folks! I received a cool message from a reader today. They saw my recent praise of Nalgene bottles and wanted to know the right way to freeze water in one. So, I thought I’d share my method.

First off, as the good folks at Nalgene explain in their FAQ, don’t fill the bottle all the way to the top. Leave it about two-thirds full. This is because water expands when it freezes, and if you fill it up too much, you might end up with a broken bottle or a shattered cap. Trust me, two-thirds is just right.

Next, keep the cap off. I know it might feel wrong, but it’s actually right. Leaving the cap off gives the freezing water some room to breathe and expand.

Now here’s a neat trick: Tilt the bottle. This provides more surface area for the water, helping to avoid any chance of it deforming and cracking the bottle as it solidifies.

And here’s the best part. Once the water is frozen, top up the rest of the bottle with cold water. Now, you’ve got ice-cold water that’ll last you all day long!

So, there you have it. Freezing water in a Nalgene bottle is easy and risk-free if you know what you’re doing.

Stay cool, my friends!