JOHN F. NORTON 369 



problems in connection with chlorination is concerned with the prevention of unde- 

 sirable flavors which are thought to be the result of the action of chlorine on phenols. 

 These enter water supplies with trade-waste contamination. More knowledge is 

 needed as to the proper methods of eUminating such tastes. This is more a chemical 

 and engineering than a bacteriological problem. 



The treatment of raw water with chlorine previous to filtration in conjunction 

 with an after-filtration dose is a problem of present day discussion and experimenta- 

 tion. The reduction of the bacterial load on the filter is one object of such treatment. 

 While results available are encouraging, more data are needed. 



GROUND WATER 



The great mass of both experimental and practical work on drinking water has 

 been concerned with public water supplies. The rural resident, however, is not bene- 

 fited by the advance in the engineering practice of water purification or by the exten- 

 sion of chlorination or other disinfecting methods, such as ultra-violet light or ozone. 

 The shallow well will remain a source of drinking water for a not inconsiderable num- 

 ber of people. While the factors concerned in the self-purification of streams have been 

 fairly well established as the result of the classical investigations of Jordan and his as- 

 sociates on the Chicago Drainage Canal and the Illinois River, as well as by the more 

 recent investigations under the direction of the United States Public Health Service, 

 our knowledge concerning the pollution of ground waters has been fragmentary and 

 impractical. A recent report from the Hygienic Laboratory' gives almost the first 

 definite information on this subject. No claim is made that the data obtained are gen- 

 erally appHcable since only one set of conditions was studied, i.e., sandy soil with 

 slowly moving water. Only a brief summary of the conclusions will be given. Back 

 coli was recovered at distances varying from i to 232 feet away from an experimental 

 trench containing excreta. This organism traveled in only one direction — that of the 

 ground- water flow. Wet weather resulted in extension of pollution; dry weather in- 

 hibited it. Bad. coli localized in an upper blanket near the ground-water table and 

 tended to filter out into the soil when the ground water fell. This organism gradually 

 disappeared if the soil remained dry. Organisms were recovered as long as two years 

 and eight months after experimental pollution. The movements of the ground-water 

 table upward and downward determined to a large extent the progression of pollution. 

 Pollution did not expand laterally (as previously thought probable) but tended to 

 contract "with the trench representing the base of a truncated section of a cone." 



The extension of such investigations is urgently needed if the water bacteriologist 

 or the sanitary engineer is to be in a position to give advice to the users of shallow 

 wells. 



THE FATE OF THE TYPHOID BACILLUS 



In connection with all problems involving the purification of polluted water sup- 

 plies, it is desirable to know with a greater degree of exactness the fate of the typhoid 

 bacillus. To be sure, conclusions are now being drawn on the basis of survival of the 

 organisms of the coli-aerogenes group, and it is argued that if this group has been dis- 



' Experimental Bacterial and Chemical Pollulion oj Wells, via Ground Water and the Factors In- 

 volved, Hygienic Laboratory Bull. 14J. 1927. 



