In 1875+, not one of the U.S. cities with a population of 100,000 or more used any kind of formal treatment for its sewage. By 1900, only two of those same cities (Worchester, MA, and Reading, PA) had installed formal designed treatment facilities.

By 1926, twenty of those same cities had sewage treatment plants. Of those facilities, nearly two-thirds of the tributary sewage was treated via Imhoff tanks, some preceded by screening. The balance (1/3) received both screening and “advanced” (activated sludge or trickly filters) treatment.

During the previous 50 years (1875-1925), the “state-of-the-art” for sewage disposal had advanced considerably more than that for sewage conveyance. Cities and towns had the benefit of knowing the actual connection between sewage and the sources of drinking water (i.e., the adverse potential impact on their health/welfare). That knowledge resulted in great strides being made in collecting and conveying sewage from/away from people’s homes, and in treating the sewage prior to its discharge either into their source of potable water or at a point near their source.