Test It Upside Down With Water

The only honest way to know if your lunch box is leakproof is to fill it with water, seal it the way you would for real, and turn it upside down over the sink.

Water is thinner than yogurt and about the same as soup, so if it holds water, it’ll hold your lunch. Soup is basically water with stuff floating in it. The stuff doesn’t leak; the liquid does.

Don’t just do the upside-down test and stop. Lay it on its side for a minute, because that’s what happens in your bag. Give it a gentle shake. Press the lid with your thumb to mimic the weight of a water bottle sitting on it. Check the corners where the lid meets the base. If you want to be extra sure, put a dry paper towel under it while it’s upside down so you can spot any slow drip.

Also, some leakproof claims just mean “won’t splash out in the car.” Those are not leakproof. And if there’s a rubber gasket, make sure it’s actually seated, not just sitting there loose. A lid that isn’t clicked down all the way will leak no matter how expensive the box is.

Finding a puddle in your bag sucks. Discovering it at the sink takes ten seconds.