Why use distillation for water? Radiation, lead, salt, heavy metals, and many other contaminants could taint your water supply after a disaster. If you try to simply filter them out, you will ruin your expensive water filter. In a scenario where the only water available is dangerous water, there aren't many options. The safest solution is water distillation. Water can be heated into steam, and the steam can then be captured to create pure water, despite many forms of contamination--including radioactive fallout. Distillation won't remove all possible contaminants, like volatile oils and certain organic compounds, but most heavy particles will stay behind.