DISINFECTANTS AND DISINFECTION 



3^7 



purification wholly unnecessary; if that is not possible, and it generally is 

 not, under our peculiar communal condition, then said questionable water 

 supply should be thoroughly sterilized and purified, according to the most 

 approved modern methods. We cannot condemn too strongly the gen- 

 erally prevalent methods of emptying the sewage of our cities and towns 

 into rivers and lakes and then again supplying this sewage contaminated 

 water to towns and cities for drinking and cooking purposes. There 

 should be an efficient state board of health cooperating with a federal 

 department, and there should be efficient and competent sanitary inspec- 

 tors to look after the water supphes of private homes, of towns and in the 

 country. 



The suitabiUty of water for drinking purposes is inversely proportional 

 to the number of bacteria present. Pure spring or well water contains very 

 few bacteria, rarely exceeding 50 per cc. Sewage contaminated water, 

 which is stiU used for drinking and cooking purposes, may contain several 

 milHon bacteria per cc. It has been proven time and again (statistically) 

 that the mortality rate (due to disease) of cities is inversely proportional 

 to the purity of the drinkmg water supply. It is self evident that water 

 purification should be considered a subject of the utmost importance. It 

 should receive more attention than it does. 



The sedimentation and filtration method for removing dirt, sand and 

 other coarser particles from the water supplies of large cities, is practised 

 and has been practised for years in many of the European cities. This 

 is satisfactory as far as it goes, but it does not go far enough. The filter- 

 ing material used (sand, charcoal, etc.) does not remove bacteria and other 

 small organisms, excepting those which are attached to the coarser par- 

 ticles remaining upon the filtering material. Furthermore, unless the 

 filter is frequently changed or sterilized, the filtering material will become 

 the breeding place of germs and thus contaminate the water still more. 



Various chemical disinfectants have been tried, but most of them have 

 proven unsatisfactory for various reasons. The use of high attenuations 

 (1-5,000,600 to 1-50,000) of copper sulphate has been highly recommended, 

 especially by the U. S. Dept. of Agriculture, and has in many instances 

 given excellent results, especially in the destruction of low forms of algae 

 and protozoa. As a means of destroying bacterial life the method is, 

 however, not a success. Dr. Kraemer and others recommend the use of 

 copper foil or plates immersed in the water as a means of destroying patho- 

 genic and other bacteria, but this method does not appear to have met 

 with any general approval. Kraemer sums up the copper foil treatment 

 of water as follows: 



I. The intestinal bacteria, like colon and typhoid, are completely de- 

 stroyed by placing clean copper foil in the water containing them. 



