184 PHARMACEUTICAL BACTERIOLOGY 



Report of the Bacteriological Examination of Water 

 Laboratory No Date Reported. . 



Town or locality 



Source of water 



Location of sampling point 



Collected by Date 



Reported to 



Number Bacteria per cc, Gelatin 20" C Agar-37.s° C 



B. Coli confirmed in cc. B. Coli Index, approximate number per cc. 



Turbidity Alkalinity as CaCOa Chlorine Hardness. . . . 



(Results in parts per million) 

 Condition of sample: 

 Remarks: 



Approved: 



Chemist and Bacteriologist Director, Bureau of Sanitary Engineering 



EXPLANATION OF RESULTS 



The laboratory results can be properly interpreted only in the light of a compre- 

 hensive field examination of the source of the water by an expert. Laboratory tests 

 can not show whether colon bacilli in the water were derived from the excreta of animals 

 or the much more dangerous sewage carrying the feces of human beings. Neither can 

 the laboratory determine whether a slight pollution at one time would mean a heavy 

 pollution at another, owing to fluctuations in the volume of sewage or to seasonal varia- 

 tions in the amount of water, disturbance of sediment by waves, etc. Careless sampling 

 and growth in transit are large factors. 



Certain conclusions can, however, be drawn from the laboratory reports alone. If 

 colon bacilli are not demonstrable in 10 cc. of the water, it may be regarded as safe 

 for drinking purposes at the time of the taking of the sample, as far as sewage pollution 

 and consequent danger from typhoid fever and other water-borne diseases is concerned. 

 If colon bacilli are demonstrable in 10 cc, but not in i cc. the water may ^be looked 

 upon as under suspicion, and a field examination is necessary to determine whether or 

 not it is safe. If colon baciUi are found in i cc. of the water, but not in o. i cc. the 

 water should be regarded as probably unsafe, and a purification process should be in- 

 stalled if the sources of contamination, animal or human, can not be removed. If 

 colon bacilli are found in o.i cc. of the water, or smaller amounts the water should be 

 considered as polluted to such a point as to be unsafe for drinking purposes. 



The B. Coli Index is the reciprocal of the smallest portion of water in which the B. 

 Coli group is confirmed. The number of B. Coli in a reasonably safe water should be 

 less than o.i cc. 



3. BACTERIA IN MILK AND IN THE DAIRYING INDUSTRY 



A. General Discussion 



Bacteria play an important part in modern dairying, and they are 

 destined to play even a more significant part in the near future. Certain 

 microbes are active in the ripening of cream, butter and cheese. Formerly 

 it was customary to let nature attend to the inoculation of the cheese, 

 resulting in a rather variable product. Now the up-to-date dairy-man 



