QUALITY, or the fitness of water for its vari ous uses, includes freedom from the specific germs of disease and from minor substances dele terious to health, an absence of turbidity and color, unpleasant taste or odors, and of all min eral matters in sufficient quantities to interfere with the various household and industrial pur poses for which the water is designed. The most serious menace to Wa t VP supplies is pol lution, which may at any time eau se an epidemic of typhoid fever and is likewise one of the chief agents in the spread of cholera. In addition, sewage pollution may give rise to various troubles of the digestive tract and render the system less able to resist various tendencies to ill health and disease. Sedimentary mutter, otherwise known as muddiness or turbidity, is gent-rally caused by clay and silt suspended ill the water. It is more offensive than dangerous, but may prove harmful if taken into the system frequently or in large quantities. Color is still
more wholly a matter of offensiveness to the eye, instead of a menace to health, than is sediment. The latter gives rise to an apparent color. which disappears with the sediment. True color, as used in water terminology, is generally a stain, rather than matter in suspension. It is fre quently due to infusions of vegetable organic matter, like leaves, grass, and peat. Odor, in any considerable degree, is less frequent and far more troublesome than either sediment or color. It is commonly due to the life processes of minute organisms in the water and is fre quently seasonal in its appearance. Sediment, odor, and taste, as well as the evil effects of sewage pollution, each yield to proper treatment, as described under WATER PURIFICATION.