Lack of Water Purification
One of the most remarkable results of the examination of water works records is the great number of systems which report no method of water purification. While of course there are certain water supplies drawn from deep well sources in which the water is sufficiently pure for human consumption, yet even here the possibility of pollution exists and should be taken seriously into consideration.
Certainly in those departments which take their supply from streams or other bodies of water exposed to the open air, no matter how apparently pure the water may be or how free from bacteriological count, there remains the danger at some point of the supply of sudden pollution from human or other sources, which may result in a serious epidemic. Because such a supply is normally pure and free from contamination, and has never shown any evidence of it, is no excuse for the water works taking any chances that this will continue indefinitely. It would be infinitely safer even if only purification through storage were restored to.
But with storage, while in principle a very efficacious method of destroying harmful germs, such as the B. Coli, as these organism are comparatively short lived and die in the course of about two months, yet there is always the risk, especially with small basins, of a quick passage of the water through the basin, through freshets or other unusually heavy current conditions, and then the purifying powers of the basin are rendered nil.
By far the safer methods are the use of filters or chlorination, or both. It is a very fine thing to be able to say that your water supply is of virgin purity, but is it worth the risk of endangering the people from the ravages of an epidemic of typhoid fever? It would hardly seem so.