Chlorination has played the primary role in protecting America’s drinking water since the early 1900’s and is responsible for a large part of the 50 percent increase in life expectancy in this century. This simple disinfection process combined with filtration led Life magazine to conclude that the water purification process as it was refined in the 20th century was “probably the most significant public health advance of the millennium.” In 1850, John Snow used chlorine to attempt disinfection in London water supplies after an outbreak of cholera. Sims Woodhead used “bleach solution” in 1897 as a temporary measure to sterilize potable water distribution mains at Maidstone, Kent (England) following a typhoid outbreak. After dramatic reduction in typhoid deaths in Great Britain, Jersey City, N.J., adopted chlorination in 1908. Other cities across the US soon followed suit and resulted in the virtual elimination of waterborne diseases such as cholera, typhoid, dysentery and hepatitis A. Prior to the chlorination of drinking water, water borne pathogens killed about 25 out of 100,000 people in the US annually, a death rate that approximates that associated with automobile accidents today.