UNSUSPECTED, UNUSUAL AND LITTLE KNOWN FACTORS IN WATER SUPPLY QUALITY [with DISCUSSION]

Until a very few years ago water works engineers and sanitarians centered their energies on the application of weapons known to be effective in a wholesale way against the scourge of typhoid fever, cholera and some other food and drink borne diseases. Among the principal of these weapons were filtration of public water supplies, pasteurization of milk supplies and typhoid inoculation. The first of these in the field and unquestionably the most important and effective was filtration of public water supplies. Its value was appreciated by a few as early as 1885 (1) but it was not until the dramatic demonstration of the efficacy of filtration in 1892 when Hamburg suffered a severe epidemic of water borne cholera, while the adjoining city of Altona was saved by filtration. From this time on public water supplies were improved by filtration and later by disinfection (with and without filtration) at an increasingly rapid rate with the result that at the present there are very few water supplies obviously liable to pollution that are not receiving systematic treatment. The effect has been a continuous reduction in deaths from typhoid fever during the thirty years of active expansion in purification of public water supplies. Perhaps all of this reduction cannot be ascribed to water supply improvement, some of it undoubtedly is due to pasteurization of milk supplies and to anti-typhoid inoculation, but there is evidence in the statistical data that safe public water supplies have had by far the major influence.