C. M. BROOM ALL 



THE LOCAL WATER SUPPLY. 



One of the most important factors in the preser\'ation of 

 the health of a community is the purity of its water suppl}^ 

 The writer has taken considerable interest in the question of 

 the water supply of this locality, and has made a number of 

 analyses in that regard. These figures, aside from establishing 

 the high standard of the Media water supply, will be useful, 

 in addition, for the purpose of detecting any deterioration that 

 may occur in the future. It is particularly with this idea in 

 view that the figures are put on record. In comparing the 

 present figures with those of the older analyses, attention 

 should be called to the fact that in 1899 the Borough of Media 

 installed a very efficient filter plant at its water works on 

 Ridley Creek, which plant has been in constant operation ever 

 since. 



Before giving the results of the analyses, a few words of 

 explanation may not be out of place for the benefit of those 

 unfamiliar with the subject. There are two distinct methods 

 of examining a water to determine its usability, one chemical 

 and the other bacteriological. The former measures certain 

 chemical products in the water that indicate the existence of 

 present or past pollution. In the bacteriological method the 

 actual number of bacteria per cubic centimeter is ascertained, 

 including both harmless and harmful bacteria, and the number 

 thus found is taken as an index of the possible danger of using 

 such water. In some cases the particular kind of bacteria is 

 determined. It is only after a judicious combination of both 

 methods that a perfectly fair judgment upon a given water can 

 be given. It is probable, however, that the chemical analysis 

 gives more nearly the true average state of the water, as ver^- 

 much larger quantities are operated upon. In addition, the 

 chemical method gives the actual chemical constitution, and, 

 therefore, its true character as a water. Any permanent change 

 in the chemical composition of the water indicates some change 

 in the environment which may be of extreme importance. 



