The Katadyn Steripen is one of those little gadgets I've come to always find room for in my pack. It uses UV light to neutralize bacteria, viruses, and whatever other little nasties are lurking in your water—no pumping, no squeezing, no waiting on tablets. You just press a button, swirl it around in your bottle for about a minute, and that's it. I usually bring it along on backpacking trips when I know I’ll have access to relatively clear water sources. It’s fast, lightweight, and super convenient.
One of the best things about the Steripen is how versatile it is beyond the trail. I’ve brought it on international trips and used it straight from hotel taps or roadside spigots when I wasn’t sure about water safety. It charges via USB, so it’s easy to keep it topped off with a power bank. For anyone who likes to travel light and doesn’t want to gamble on sketchy water sources, it’s a great piece of gear to have in your kit.
The one thing I would point out is that it's obviously not going to be removing any debris, but you can find creative ways to filter that out. I've kept clean bandanas in my pack for this very reason in the past. It's fast, simple, and lightweight.