One of the great inconveniences of travelling to the USA is not being able to bring your liquids through security. After passing through the body scanner, you’re probably quite parched, and find the only options for liquid replenishment are an $8 bottle of “fancy” water, or a very low (and very low-pressure) water fountain outside the toilet.
There is a loophole, however, for getting your precious liquids through airport security. The TSA’s “3-1-1" liquids rule applies only to liquids, not solids. You can freeze your liquids, and as long as they aren’t slushy, you can mosey on through security. (The TSA’s own website confirms this.)
Here's the relevant extract:
Frozen liquid items are allowed through the checkpoint as long as they are frozen solid when presented for screening. If frozen liquid items are partially melted, slushy, or have any liquid at the bottom of the container, they must meet 3-1-1 liquids requirements.
Now, you’re probably thinking that this is just a way to bring a solid block of ice into the airport, which doesn’t help your thirst at all. Well yes, that’s true, so I’ve compiled a list of ways this trick is actually useful:
Fill your bottle halfway before freezing, then add water once you pass security, and you now have cold water.
Freeze an ice pack and pack a small cooler of refrigerated food to eat on the plane.
Freeze a delicious sweet beverage and let it thaw to drink over the course of your long plane ride back home.
There are, of course, things that I do not advise that you freeze, like shampoo, hair gel, or peanut butter. So either pack fewer than three 100ml of peanut butter, or just check it on through to your final destination.