Thursday, February 5, 2009

The Advent of Municipal Water Treatment

Long before Snow linked cholera deaths to poor water quality, people were beginning to suggest that pure water be provided to every household through some sort of citywide water filtration. The supposition that every person deserved clean water to drink and bathe in was related to the general philosophical themes of the Enlightenment period in Europe. During the Age of Enlightenment of the sixteenth through eighteenth centuries, philosophers ruminated over the natural rights of all humanity. The right to clean, pure water began to be associated with these innate rights of all humanity. Such philosophical discussions led the French scientist La Hire to propose that every French household have a sand water filter installed that would provide clean water to that household. Sand filters had become the most popular method of water filtration throughout many European towns.

About 100 years after La Hire first suggested that all citizens should be given the right to pure water, government officials in the United Kingdom began to wonder, also, if every household in their domain should be provided with some kind of filtered water. In 1804, the first citywide, municipal water treatment plant was installed in Paisley, Scotland (Baker & Taras, 1981). This plant would provide filtered water to every household within the city limits. The Scottish water treatment plant depended upon slow sand filters designed by Robert Thom, an important scientist of the Scottish Enlightenment. In 1827, James Simpson, an English scientist, created a similar design to Thom’s, and the Simpson water filter models were soon implemented in municipal water treatment plants throughout England.

The slow sand water filters designed by Thom and Simpson were very large and required frequent and extensive cleaning. Because of the growing need for filtered water, scientists in the United States designed a rapid sand filter in the late nineteenth century (Baker & Taras, 1981). The rapid sand filter was cleaned by powerful jet streams of water, greatly increasing the efficiency and capacity of the water filter.