Sanitation and water treatment

node · earth · Britain and North America first; now global

The combination of piped clean water, sewerage separated from drinking supply, sand filtration and — from around 1908 in the United States — chlorination, together with refuse removal and housing regulation. It is the largest single contributor to the modern mortality decline and it arrived largely before germ theory was accepted: Edwin Chadwick's 1842 sanitary report argued from mortality statistics while holding the wrong mechanism, miasma, and prescribed exactly the right remedy. Cutler and Miller's analysis of major United States cities between 1900 and 1936 attributes roughly half of the total mortality decline, and a substantially larger share of the infant mortality decline, to clean water technologies alone. The intervention is unglamorous, municipal, capital-intensive and almost entirely invisible in popular longevity discourse, which is a reasonable measure of how badly that discourse is calibrated.