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



283 



Although usually undesirable sources of water supply, rivers 

 are necessarily used in some parts of the Philippines, especially 

 in districts where an abundant supply of good artesian water 

 is not available. The Manila and Cebu water-supply installa- 

 tions are the best examples of this type. 



Some of the results shown in Table I have already been dis- 

 cussed by Bliss,^ who pointed out that the variations in seasons 

 appear to have surprisngly little effect on the chemical constit- 

 uents of surface water. The bacterial count often shows enor- 

 mous increase after a heavy shower. The amount of insoluble 

 suspended matter increases appreciably in rainy weather, and 

 the oxygen-consuming capacity appears to do the same. 



Table II shows the daily variation in bacteria count, as 

 measured in the Manila water supply, and demonstrates that 

 water from surface streams, no matter how well guarded, is 

 not entirely satisfactory, since it is always subject to sudden 

 contamination. 



Table II. — Bactei-iological examinations of the city of Manila water supply. 



Date. 



Colonies. 



Presump- 

 tive test. 



Bacillus 

 coli. 



Amcebae. 



Ciliates. 



Flagel- 

 lates. 



1913. 















Apr. 12 



258 



— 



— 



+ 



+ 



+ 



13 



216 



+ 



— 



+ 



+ 



+ 



14 



356 



+ 



— 



+ 



+ 



+ 



15 



256 



+ 



— 



1~ 



+ 



-1- 



16 



1,908 



a. 



— 



+ 



H- 



+ 



17 



2,289 



H- 



— 



+ 



+ 



+ 



18 



1,145 



+ 



(») 



-(- 



+ 



+ 



19 



928 



+ 



— 



+ 



-r 



H- 



20 



1,654 



-t- 





-r 



+ 



+ 



21 



3.053 



+ 





-i- 



-f 



+ 



22 



768 



-f 



— 



H- 



-1- 



-i- 



23 



1,040 





— 



+ 



-U 



+ 



24 



800 



-1- 



— 



+ 



-r 



H 



25 



763 



+ 



— 



+ 



+ 



^L 



26 



780 



+ 



— 



+ 



+ 



4- 



27 



976 



+ 



— 



+ 



+ 



+ 



28 



941 



-i- 



— 



_L 



+ 



+ 



29 



1,145 



+ 



— 



+ 



-1- 



+ 



30 



1,908 



+ 



— 



+ 



-i- 



+ 



May 1 



1,152 



4- 



— 



+ 



+ 



+ 



2 



608 



+ 



— 



+ 



+ 



+ 



3 



656 



— 



— 



+ 



-1- 



+ 



4 



422 



— 



— 



+ 



H- 



+ 



5 



381 



— 



— 



— 



+ 



+ 



6 



464 



+ 



— 



+ 



+ 



+ 



• Bacillus coli group. 



''Pub. P. I. Bur. Govt. Lab. (1905), No. 20, 39. 



