BAGTERIA AND RURAL WATER SUPPLIES 9 



to exist between this group and E. coii. It appears to be a species of E. coli that 

 can utilize sodium citrate. 



The section of this bulletin that follows immediately is a general summary of 

 some of the experimental work that was done in the effort to arrive at a better 

 understanding of the relationship of coliform bacteria to rural water supplies 

 in order that more intelligent interpretations of results might be made. At the 

 end are placed comprehensive abstracts of the several studies, to supply essential 

 technical data for those who want them. These abstracts are arranged on the 

 basis of logical relationship and sequence, and are designated by capital letters. 

 These designations are referred to in the general summary to relate it to the 

 abstracts. 



SUMMARY OF EXPERIMENTAL STUDIES 



The experimental studies reported in this bulletin developed logically, step 

 by step, as is indicated by the order of discussion of the subjects in this summary, 

 and of the arrangement of the abstracts. 



The first study (A) was concerned with results of tests of rural water supplies. 

 For some years numbers of water samples from farms and rural homes have been 

 brought into this laboratory to be tested bacteriologically. The "Standard 

 Methods" procedure has been employed. Gradually, as the results of tests 

 accumulated, it began to appear that a disproportionately large number of water- 

 supply sources were being condemned on the basis of the laboratory tests as being 

 unfit for household use. 



This department has no extension service, but it was possible sometimes to 

 make inspections of the locations, and it often happened that inspection failed 

 to reveal any cause for the water being unsafe for use in the home. Considering 

 all of the evidence, it seemed that the Standard-Methods test was too exacting 

 for privately owned rural water supplies. That was the inspiration for the 

 studies that followed. 



The laboratory study was begun with a collection of 223 cultures of coliform 

 bacteria from 172 water samples brought in for routine testing. The "Imvic" 

 tests were applied to these cultures with the result that only 60.5 percent of 

 them were classified as colon bacilli and the balance were aerogenes bacilli or 

 intermediates of the coliform group. Considering that the colon bacillus indi- 

 cates pollution from sewage, and that the aerogenes bacillus and intermediates 

 usually are from the soil, nearly 40 percent of the cultures must have come from 

 surface wash. If they indicated sewage pollution at all, it was likely that it had 

 been remote both as to time and location. On the basis of this survey, it seemed 

 that rural raw-water supplies should not be condemned without a sanitary survey 

 of the premises unless the colon bacillus itself is found in the water samples ex- 

 amined. 



A supplementary study was made (B) of some abandoned wells located in the 

 hilly country east and northeast of Amherst. This region once was settled and 

 farmed, but the land is poor and for years it has been largely abandoned as farm- 

 ing land. Most of it has been used for timber land, and occasionally for hay 

 fields. Most of the homes have been removed, or have fallen down, and it has 

 been many years since any one has lived at the sites employed for the study. 



Seven wells were selected. All were located in open hay fields, and were so 

 situated that little surface water would flow into them. The fields were not 

 fenced and consequently no domestic animals were pastured in them. Hence, 

 there was little chance for dangerous pollution to get into the water. The wells. 



