Lawrence Experiment Station

The Lawrence city filter, 1893 This is where American water treatment proved itself with numbers. Typhoid in Lawrence and neighboring Lowell, Massachusetts, killed more than 200 people in 1890 and 1891. The state's experiment station, directed by engineer Hiram Mills, had been studying water and sewage treatment there since 1887, and the city's slow sand filter went into service in September 1893. Once it was running, the town's typhoid death rate fell almost 78%. Few works on this list have a cleaner before and after.