This widespread problem of water pollution is jeopardizing our health. Unsafe water kills more people each year than war and all other forms of violence combined. Meanwhile, our drinkable water sources are finite: Less than 1 percent of the earth's freshwater is actually accessible to us. Without action, the challenges will only increase by 2050, when global demand for freshwater is expected to be one-third greater than it is now. Still, we're not hopeless against the threat to clean water. To better understand the problem and what we can do about it, here's an overview of what water pollution is, what causes it, and how we can protect ourselves.