The purification of municipal water supplies by filtration has been practiced for over seventy years. Apparently the first filter of considerable size was that constructed by the city of London in 1829, and that city now has about 120 acres of sand filter beds. Berlin, Germany, built water works and sand filters in 1856, fifty years ago, and at the present time practically all the important cities of Great Britain and Germany filter their water supply if this water is taken from a surface source. Filtration of public supplies is widely practiced in other countries, especially Belgium and Holland. Even Russia has several large municipal filters; a recent article in the Engineering Record describes large sand filtration plants in Japan, while in India and Egypt a number of large municipal supplies are treated by mechanical filters.
The first large municipal filter in America was constructed at Lawrence, Mass., in 1892-93,