The Handbook of Public Water Supplies prepared by the American Water Works Association, Inc. (Third Edition, 1971) has a few paragraphs on disinfection by metal ions. It includes a few remarks on its history.
According to this handbook, the oligodynamic properties of silver were described by Raulin in 1869 in his article The Chemistry Of Vegetation, Sci. Nat., 11:93 (1869). In 1893 the Swiss botanist Nageli observed the disappearance of Spirogyrae from waters containing minute quantities of finely divided silver precipitated from one of its salts. The AWWA Handbook mentions that M.N. Baker's book, The Quest For Pure Water (Lancaster Press, 1948) indicates that the first paper in English on the use of silver for water disinfection was published in 1932 in England. Baker writes that four papers on the subject were published in the United States between 1934 and 1936, one originating in Russia and the other in Poland. The latter deal with experiments with "filters containing metallic silver, with solutions of silver salts and with electrocatynization whereby finely divided silver was produced by an electrolytic system."
