This article summarizes the history of water purification including: Egyptian, Greek, and Roman efforts at water purification; the dark ages and Renaissance times; the first water filter patent invented in 1745 by Frenchman Joseph Amy; the first modern water filter plant invented in 1804 by John Gibb in Scotland; invention of the slow sand filter in the 1820s in London by James Simpson; the first American efforts at filtration in post-Civil War years; the installation of slow sand, and then rapid sand filters in the U.S.; the advent of the era of safe water with the use of Chlorine; and, 20th century consumer and government demands.