I found this article/fact sheet from the World Health Organization website, called "Arsenic in drinking water" at http://www.who.int/en/.
This article is about arsenic which is a semi-metallic naturally-occurring chemical. It is found in water which has flowed through arsenic-rich rocks into underground water supplies. It is odorless and flavorless. If poisoned, a person will usually die. There are many other health problems associated wiht arsenic, such as cancer, kidney failure, skin thickening, etc. "Environment Protection Agency of The United States of America has estimated that some 13 million of the population of USA, mostly in the western states, are exposed to arsenic in drinking- water." There are technologies used for arsenic removal in water supply, but it is costly and requires technical expertise. People just need to be more aware of the problem and take drastic measures to prevent themselves and their families from arsenic poisoning because it can happen.