A recent Scientific American article, “Access to Safe Drinking Water,” reveals just how complicated the answer to that question is. In historical terms, water supplies today are extraordinarily safe in much of the developed world. As the opening paragraphs put it,
In 1848 and 1849 up to a million people in Russia and 150,000 in France died of cholera, the classic disease of contaminated water. Typhoid fever, another disease transmitted through water, was most likely responsible for the deaths of 6,500 out of 7,500 colonists in Jamestown, Va., early in the 17th century; during the Spanish-American War, it disabled one fifth of the American army.
Today waterborne disease is no longer a major problem in developed countries, thanks to water-purification methods such as filtration and chlorination and to the widespread availability of sanitary facilities. But in developing countries, waterborne and sanitation-related diseases kill well over three million annually and disable hundreds of millions more, most of them younger than five years of age.
It is ironic that while environmentalists in the West obsess over the effects of trace elements of chemicals in the water supply that hundreds of millions of people face conventional risks which have been wiped out in the West.