Luckily water is relatively easy to find in most places. Unfortunately, most water is not suitable for drinking. In fact, less than 1-percent of the Earths water is drinkable. In other words, don't drink from that river, stream, or rain barrel without some serious filtration. Or a LifeStraw.
The LifeStraw is an small and portable water filtration that works in a way that most humans are already familiar with. You simply use the LifeStraw like a regular straw. The LifeStraw removes 99.9999% of water bacteria and can filter particles at the 0.2 micron level.
Each LifeStraw water filter will work for about 1000 liters of contaminated water. There are no batteries to charge, no moving parts, no chemicals, and while it is made of plastic there is no BPA. And, this water filter which is perfect for backpacking is only $23 here.
The only downside is that you have to suck pretty hard and takes about 3-5 seconds before the first drop of water makes it through the straw. Video of the LifeStraw in action after the break.