- Cholera, typhoid fever, dysentery, and hepatitis A killed thousands in the U.S. annually before water chlorination and filtration became a routine part of municipal water treatment
- A 2004 study of disease rates in US cities found clean water to be the reason for the rapid decline in urban death rates during the late 19th and early 20th centuries. By 1941, 85% of US cities treated their municipal supplies with chlorine, to the great benefit of public health.