The Value of Pure Water 55 



attributes which have to be taken into consideration, and because 

 these attributes vary in importance in every instance. "Pure and 

 wholesome water" is not a substance of absolute quality. Strictly 

 speaking, pure water does not exist in nature; all natural waters 

 contain substances either in solution or suspension; and in propor- 

 tion as these substances are present, and in proportion as they are 

 objectionable in character, the water is impure. Definitions of pure 

 and wholesome water, therefore, generally state what foreign sub- 

 stances shall not be present, or in what amounts they are permis- 

 sible, instead of defining the positive qualities which the water shall 

 possess. 



Unquestionably the term "pure and wholesome water," as ordi- 

 narily used, relates to water intended to be used for drinking. Such 

 a water must be free from all poisonous substances, as the salts of 

 lead ; it must be free from bacteria or other organisms liable to cause 

 disease, such as the bacilli of typhoid fever or dysentery; it must 

 also be free from bacteria of fecal origin, such at B. coli. In other 

 words, the water must be free from poisonous substances, from 

 infection, and even from contamination,* Besides this, it must be 

 practically clear, colorless, odorless and reasonably free from objection- 

 able chemical salts in solution and from microscopic organisms in 

 suspension. Moreover, it must be well aerated. Color, turbidity, 

 odor, dissolved salts, etc., may be permissible to a small degree with- 

 out throwing the water outside of the definition of pure and whole- 

 some waters. In these minor matters local standards govern up to 

 a certain point, and it is in regard to them that differences in the 

 judgment and experience of analysts lead to different classifications. 



When it comes to using water for other purposes than for drinking, 

 other attributes have to be considered. Hardness makes a water 

 troublesome to wash with and to use in boilers; iron makes trouble in 

 the laundry; chlorine corrodes pipes and makes work for the plumb- 

 ers; the presence of the carbonates and sulphates of lime and mag- 

 nesia affects the paper-maker, the brewer, the tanner, the dyer, the 

 bleacher; soda causes a locomotive boiler to foam, and affects the use 

 of the water for irrigation. All of these constituents, and others which 



♦By this term is meant pollution with fecal matter. Contamination must be considered as potential 

 infection. 



