Water. We drink it and cook with it; it soaks into our skin and hair in the shower or bath. But as I found out recently, studies have discovered everything from toxic chemicals to pharmaceuticals in our drinking water. After researching drinking water in my neighborhood, I found that our zip code registered high levels of potentially toxic chemicals—including chlorine dioxide, which is a commonly used drinking water disinfectant. With a simple chlorine test that I got at the hardware store, I saw firsthand how much chlorine was in our drinking water, and how much we were absorbing in the bath and shower. At that point, I was convinced: I…