IX, A, 4 Cox et al. : Water Supplies in the Philippines 343 



has practically never been free from them. However, that the 

 amoebse ordinarily growing in water cause dysentery in man has 

 been disproved." 



PURIFICATION OF WATER SUPPLIES 



As all natural waters in the Philippines, with the probable ex- 

 ception of most flowing artesian wells, contain various organisms, 

 it is evident that, to be perfectly safe, water must be sterilized or 

 at least so treated that harmful organisms will be destroyed. 



Distillation. — The Americans soon introduced the use of dis- 

 tilled water for drinking purposes, both the military and civil 

 governments operating their own distilling plants. The latter 

 furnishes the public with drinking water at the rate of 1 centavo 

 (5 mills U. S. currency) per liter. Recently, distilled water has 

 been largely replaced by water from artesian wells known to be 

 pure. 



Boiling. — Boiling is perhaps the simplest and most universal 

 safeguard in so far as contamination of water due to living organ- 

 isms is concerned, and is necessary in the Philippines in localities 

 where distilled water or water procured directly from sources 

 of known purity is not available; but general information con- 

 cerning the subject is not widespread, and the cost of fuel is so 

 high and the cooking facilities in the average home are so poor 

 that in some instances it is difficult for families to cook their 

 food. The peculiar taste of boiled water, superstitions regarding 

 its harmful character, and the lack of a comprehension of the 

 purpose of the boiling militate against its use. 



Filtration. — So far very little work has been done in the Phil- 

 ippines on the filtration of public water supplies, owing to the 

 urgency of other work and to the scarcity of large water-supply 

 installations. Filtration on a large scale has not yet been at- 

 tempted, but the need of some adequate system of purification 

 has been felt in the city of Manila, and it is probably only a 

 question of time before some filtration system will be installed. 



Ultra-violet light. — Preliminary experiments on sterilization 

 with ultra-violet light have been very encouraging, and further 

 investigations are contemplated with the sterilizing outfit re- 

 cently installed at the Bureau of Science. 



Copper sulphate. — The purification of the Manila water supply 

 with copper sulphate was investigated in 1906 and again during 

 an interruption of the service of the Montalban water supply in 



"Walker, loc. cit. 



