A BACTERIOLOGICAL EXAMINATION OF CERTAIN ARTESIAN 

 WELLS IN RIZAL, CAVITE, AND BULACAN PROVINCES, P. I. 



By Marshall A. Barber 

 (From the Biological Laboratory, Bureau of Science, Manila, P. I.) 



Since artesian wells have become one of the chief sources 

 of potable water in Rizal, Cavite, and Bulacan Provinces, P. I., 

 it was thought advisable to make a careful bacteriological test of 

 a number of them for the presence of pollution. In addition, 

 it seemed of scientific interest to compare the numbers of bac- 

 teria found in different waters from these sources. These wells 

 may fairly represent similar wells in these and other provinces. 

 In all, 34 wells were examined, 22 of them flowing and 12 pump- 

 ing. Some of the pumping wells were formerly flowing, and in 

 all flowing wells, as a rule, there has been a diminution in the 

 rate of flow since the wells were sunk. Among the 12 pumping 

 wells are included 2 — Malolos (Plaza Malolos) and Bocaue — which 

 flow intermittently at the present time. In some of the wells 

 the flow is said to be greater at high tide. 



In practically every case nutrient media were taken to the 

 well itself, and the water transferred to most of the tubes or 

 plates directly from the source. Whenever practicable, the tip of 

 the sterile pipette was brought directly into the flowing stream in 

 taking samples. Usually an additional sample was packed in 

 ice and transported to the laboratory for additional or confirm- 

 atory tests. It was early found that the water of the flowing 

 wells was nearly sterile; so, in order to get some comparisons, 

 a larger range of tests was made and larger quantities of water 

 sown than an ordinary sanitary analysis would require. 



In all agar tests the water was well mixed with liquified agar 

 cooled to 42" C. Plate cultures were made only where stated 

 in the table. Plates were kept at high room temperature (28° 

 to 32° C). All other cultures were incubated three days, then 

 removed to room temperature. The rate of flow was estimated 

 by noting the time required to fill a can of approximately 5 

 gallons' (19 liters') capacity. 



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