In 1925, the Illinois State Water Survey published a Bulletin describing the quantity and quality of public ground-water supplies, based on reports from incorporated municipalities. This report gives the history of the public supply organized alphabetically by municipality, with chemical and mineral analyses of samples from each supply. Supplements were published to cover new supplies developed after the 1925 report, and in 1950, Bulletin no. 40 was issued as an update to Bulletin no. 21.