900 million people in the world are without access to safe drinking water. That’s a serious problem. Announced to the world in 2005, the LifeStraw invention purifies water instantly. As the user sucks on it like a straw, 99.9999% of waterborne bacteria and 99.9% of parasites is removed.
It costs $20 in the USA, and is cheaper or subsidized for places in need. That makes it a relatively inexpensive solution that could serve a lot of people.