I have found a great deal about water purification dealing with biological contaminants; not much on acquiring water from industrial or farm areas. This is highlighted more because of the disaster in Japan. Major disasters like Katrina and the earthquake in Japan pollute the water with much more than bacteria and viruses. In many parts of the world (and even our country) all ground water must be considered polluted.

How do you remove chemicals and heavy metals? Is it even worth trying? Are there any products which can do it efficiently? Will they fit in your BOB? Do they require power?