I know a lot of folks who won't go near tap water. They are terrified of dirty water and need to make sure it's filtered. While that's not an unreasonable request, it's sometimes difficult. What if there is no water filter? Or what if you're traveling? This is where the geeky iStraw comes in hand. This compact, portable device purifies water and reduces up to 99.99999% of all waterborne bacteria. It's good for up to 500 liters of water and supposedly leaves no after taste.
I think this is pretty fantastic and can see where it would come in handy. Sure your friends might laugh at how over-cautious you're acting, but who'll be laughing when they get sick from drinking the water and you don't? Available for £19.99 (approximately $40).