10 MASS. EXPERIMENT STATION BULLETIN 383 



in sewage contamination. Modern knowledge of water sanitation, requir- 

 ing a tight tile curbing and a tight inetal or stone cover, in addition to 

 proper location of the supply, results in a fully protected drinking water 

 supply. 



As stated previously, spring water as it emerges from the ground is 

 generally of high quality. Contamination of the supply occurs only after 

 the water has emerged from the ground, and it is for the most part of 

 the surface-drainage type rather than the sewage type. Proper excavation 

 back to the actual point where the water emerges and a well-constructed 

 spring house will prevent this subsequent contamination. 



The records show that in practically every case where contamination 

 occurred in a driven well it could be traced to a poor location. It is true 

 that soil will act as a natural filter for the water percolating through it. 

 However, when it becomes saturated with impurities, it tlien ceases to 

 act as a filter. Further, even though the source of the impurities was 

 removed, it still would take the soil a considerable length of time to 

 purify itself. The answer to this problem is to so locate the well in respect 

 to the waste disposal systems from the house that no contamination from 

 these sources can gain access to the well, or to the soil immediately sur- 

 rounding the well. 



Table 2. — Location of supplies tested, by counties, and the number 



AND percentage SHOWING CONTAMINATION. 



Total 



Number Number Number not Percent 



County Tested Contaminated Contaminated Contaminated 



Nantucket 



Dukes 



Plymouth 9 9 



Bristol 17 7 10 41 



Barnstable 118 29 89 24 



Norfolk 3 1 2 33 



Suffolk 8 7 1 87 



Middlesex 21 6 15 28 



Essex 17 11 6 64 



Worcester 223 121 102 54 



Hampden 104 41 63 40 



Hampshire 235 118 117 50 



Franklin 184 84 100 45 



Berkshire 11 29 48 2>1 



Totals 1,016* 454* 562* 44" 



* Includes drilled wells. 



