XI, A, 1 



Heise: Water Supply of Manila 



or for any sedimentation except thet naturally occurring at 

 Montalban and at the reservoir. The only method of purification 

 employed consists of the addition of chloride of lime to the water, 

 just as it leaves the reservoir. 



QUALITY OF THE WATER PROM MONTALBAN 



Chemically the quality of the water from Montalban leaves 

 little to be desired so far as its use for city supply is concerned. 

 The water is moderately hard, usually slightly turbid, and has a 

 low mineral content. Its turbidity is not great enough to be 

 objectionable, but as it is due mainly to extremely fine particles 

 of clay and silt, sedimentation is comparatively slow. As al- 

 ready pointed out by Bliss, * seasonal variations in the water 

 are surprisingly slight, in spite of the heavy rains of the wet 

 season, which greatly change the amount and appearance of 

 the water coming from the watershed. 



Typical analyses of the Manila water, coupled, for comparison, 

 with older analyses of the Mariquina supply, are shown in 

 Table I. 



Table I. — Analyses of Manila water supply. 



[Results expressed as parts per million.] 





1903 a 



1906b 



9109 c 



1913c 



Mini- 

 mum. 



Maxi- 

 mum. 



Total solids .. 



153 



127 



16 



220 

 190 

 46 



215 



157 

 125 

 32 



154 



Fixed solids 



Loss on ignition 







Silica (Si02) 



44.7 



23.7 

 1.7 



81.2 

 6.5 



12.7 

 1.9 

 

 139 



13.8 

 0.046 

 trace 

 0.03 

 0.116 



Oxides of iron and aluminium. 

 Calcium (Ca) 













16.4 

 5.4 

 8 

 2.3 





Magnesium (Mg) 









Sodium (Na) 









Potassium (K) 









Normal carbonates (as CO3) 









Bicarbonates (as CO3) 











Sulphates (SO4) 







18.7 





Nitrates (N) .. 



trace 

 

 



0.031 

 0.65 

 58.8 

 2.1 



0.36 

 trace 

 0.036 

 0.100 

 2.20 

 109 

 4.4 



0.02 

 trace 

 0.12 

 0.1 

 1.65 

 90 

 3.1 



Nitrites (N) 





Free ammonia (N) - 





Albuminoid ammonia -- 





Oxygen consumed 





Total hardness (as CaCOs) 



Chlorine (01) 



99 

 3.9 





4.1 





• Analysis by C. H. Bliss, chemist. Bureau of Science. 

 •• Analysis by L. A. Salinger, chemist. Bureau of Science. 

 = Analysis by V. Q. Gana, chemist. Bureau of Science. 



*Pub. P. I. Bur. Govt. Lab. (1905), No. 20, 10. 



