Water Filtration Works

Abstract

FILTRATION, which is generally regarded as an essential process in the provision of domestic water-supplies for large towns in England, especially when rivers constitute the source of supply, has been neglected to a considerable extent in the United States, and, therefore, the publication of a book, by an American engineer, dealing wholly with this subject, will be particularly valuable if it should lead municipalitiss in the United States to the more general adoption of this safeguard against the distribution of water to large populations in a condition dangerous to health. Polluted river waters, in their natural condition, have proved very fatal to our troops in South Africa, as shown by the high rate of mortality from enteric or typhoid fever; and the author, at the commencement of his book, draws a very striking contrast between the annual death-rate from typhoid fever per 100,000 persons in cities supplied with pure or filtered water, such as the Hague, Munich, Dresden, and Berlin, with a typhoid death-rate of only from 4.7 to 7, and Washington, Louisville, and Pittsburg, supplied with unfiltered river water, where the yearly typhoid death-rate for several years has averaged 71, 74, and 84, respectively, per hundred thousand of population. River waters are to;some extent purified by natural agencies during their downward flow if no fresh causes of contamination, are introduced, depending on the extent of their origna1 pollution and the length of their uncontaminated flow; and. the impurities in suspension may to a considerable extent be removed by causing.the water to remain at rest in a settling basin for a certain period before distribution, so that the larger, heavier particles are deposited at the bottom of the basin. Generally, however, after this subsidence has taken place, the finer, lighter particles and microorganisms remain in suspension in the water, as well as substances in solution; and the final purification can only be effected by filtration, assisted often by aëration, and sometimes by chemical processes.

Water Filtration Works.

By James H. Fuertes. Pp. xviii + 283. (New York: John Wiley and Sons; London: Chapman and Hall, Ltd., 1901.) Price 10s. 6d.