Use a thermos, not a Tupperware

The trick is to use a proper leakproof thermos and pack it upright — not just any Tupperware.

Most soup spills happen because you’re using a lunch container with a clip-on lid. It might feel sealed when you shake it, but heat and changes in pressure will flex that lid enough to seep a little soup into your bag. By the time you open your backpack, everything smells like tomato.

So get a wide-mouth vacuum thermos or a screw-top jar with a silicone gasket. Fill it no more than 80% full, and let the soup cool a little before you seal it — hot soup creates steam pressure that actually works against the seal. Screw the lid on tight, and if you’re paranoid, pop the thermos in a small ziplock bag before it goes in the lunch box. Pack it upright too, wedged between other containers or a folded towel so it doesn’t roll on its side.

That’s it. No foil, no tape, no plastic wrap under the lid. A thermos handles the whole job, and your lunchbox stays dry.

Your bag will thank you.