Ziplock bags don’t take up much space and can protect your valuables from water. There have been cases when a phone being stored in something waterproof saved people’s lives. Plus, they also can be used to purify water under the sunlight if your reusable water bottle isn’t transparent. In everyday life, you can keep a piece of paper, like your medical information, a list of your allergies, or relatives’ numbers in these bags in case you need them in an emergency.