2 The Philippine Journal of Science i9X6 



(15.7 miles) from Manila, and the watershed above that point, 

 about 1,550 square kilometers (60 square miles), was reserved 

 from settlement. The minimum daily flow in the river during 

 the dry season is estimated at 41,700 cubic meters (11,000,000 

 gallons). The storage capacity of the dam was estimated at 

 something over 4,700,000 cubic meters (1,250,000,000 gallons), 

 although this figure is not effective owing to leakage at the dam, 

 a loss which fissures and cracks in the limestone composing the 

 walls and floor of the gorge make more or less unavoidable. A 

 new reservoir having a capacity of about 206,000 cubic meters 

 (54,500,000 gallons) was constructed on high ground near 

 the city. 



With this arrangement Manila now has a complete gravity 

 system, the water flowing from Montalban to the new reservoir, 

 thence to the city distribution system. The consumption of 

 water (October, 1915) is about 57,000 cubic meters (15,000,000 

 gallons) a day, corresponding to a per capita consumption of 

 approximately 220 liters (58 gallons). At this rate the storage 

 capacity of the new reservoir is about three and one-half days. 



There are generally enough rains in the dry season to main- 

 tain a supply of water adequate for the city's needs, and if it 

 were not for leakage at the dam, the supply would probably 

 be sufficient; in periods of extended drought, however, it fre- 

 quently happens that there is not sufficient water from Montalban 

 to supply Manila. At such times it becomes necessary to aug- 

 ment the supply by using the old Santolan pumping station and 

 the old deposito, whose capacity is now about 72,000 cubic meters 

 (19,000,000 gallons). While the Santolan system is in opera- 

 tion, guards are placed along the banks of Mariquina River to 

 prevent contamination of the water so far as possible. 



The new supply system is a tremendous improvement over 

 the old installation. The Bureau of Health ^ has pointed out that 

 there were 300 per cent more deaths from intestinal diseases 

 in the years just preceding the installation of the new supply 

 system than in the years immediately following, and has shown ^ 

 further that when the inadequacy of the Montalban supply made 

 it necessary to resort to the old Santolan system to supplement 

 the city supply a marked increase in the death rate occurred. 

 At the time these observations were made, the water was used 

 just as it came from Montalban, no attempt being made to 

 purify it. 



At the present time there is no provision made for filtration 



* Ann. Rev. P. I. Bur. Health (1912), 5. ' Ibid., 47. 



