INVESTIGATION OF DRINKING WATER SUPPLIES 167 



of interest to enumerate some of the most common errors that 

 are found associated with water supplies. The errors referred 

 to are briefly summarized as follows : 



1) The use of surface waters without treatment, as all 

 such waters must be considered open to contamination. The 

 sanitary policing of such sources is usually impossible or im- 

 practical. 



2) The installation of water purification plants in localities 

 where underground supplies were available and would have 

 provided a safer source. 



3) The installation of water purification plants by local 

 authorities who have little or no understanding of the theoreti- 

 cal and practical side of the treatment nor the difficulties 

 attending the operation of these plants. Many such plants 

 have been installed and the authorities believed them to be 

 equipped with automatic devices which would insure an ef- 

 fluent of good sanitary quality. This impression is erroneous 

 since these plants require the most careful attention by trained 

 operators at all times during the operation. 



4) The installation of hypochlorite or liquid chlorine plants 

 to purify water that cannot be properly purified by these 

 chemicals because filtration is required to render it suitable for 

 such treatment. 



5) The addition of hypochlorite or liquid chlorine to raw 

 water as it enters a filtration plant rather than to the effluent. 

 This practice often makes very difficult the administration of 

 these chemicals in proper amounts. 



6) The failure to keep on hand duplicate parts of im- 

 portant equipment, especially parts of chlorine apparatus that 

 are likely to get out of repair. The lack of such parts may 

 make it necessary to allow untreated water to be discharged 

 into the distribution system. 



7) The installation of by-passes around water purification 

 plants by which untreated water can be admitted into the 

 system without passing through the plants. 



8) The improper operation of water purification plants 

 by unskilled or inefficient operators. 



