The Watek-Suim'ly of Towns kv the Tuorics 



Chiekly fuom the Bacteuiolouical .Staxui'oixt 



AS Illl'stuated uv the Watek-Sui'I'ly ok Khautoum 



BY 



The DiUECTOK 



As events are trending there may yet, in certain instances at least, be some 

 justification for those who express a lack of faith in the value of Bacillus coli ciitniiinnis 

 as an indicator of pollution of a potable water. This organism has been put forward 

 by Houston, Savage, Jordan and others^ as, with due restrictions, a reliable test of purity 

 or otherwise of a water-supply. Their view has recently received confirmation at the hands 

 of Portuguese investigators, by Guiraud and Mandoul- in France, and has also been ably 

 upheld by Fromme^ in an exhaustive paper in the Ze.itfchfift fur Uijgunie, the result of 

 a lengthy experience and many investigations. Similar conclusions were reached by 

 Hilgermann.-* On the other hand there seems to be a growing tendency to regard it as 

 mistaken, and I need merely mention recent expressions of opinion by Starkey^ and Eussel 

 and McLean'' in this connection, while the majority of German workers consider the bacillus 

 ubiquitous. In this connection a recent paper by Gartner' may be consulted. One has . 

 neither the time nor the desire to plunge into this vexed question so far as water-supplies signiticanLe uf 

 generallv are concerned, but would direct attention to it as regards water-supiilies in the '" ' . 

 Tropics. Until recently, records of bacteriological investigations of water-supplies in in water 

 tropical countries have been few and far between. This is natural enough as, hitherto, 

 facilities have not existed for work on those lines, but with the establishment of well- 

 equipped laboratories in many parts of the tropical world it is probable that ere long 

 many statistics will be available and that we will be in a better position to appreciate 

 the differences which undoubtedly occur in the bacterial content of tropical waters as 

 compared with those in temperate climates and the possible necessity for modifications 

 of existing standards of bacterial impurity. 



In the Tropics the water-supply of a town or village is usually derived from one of 

 two sources — from wells, usually shallow wells, and from rivers or streams. 



In Khartoum, for I intend to take the problem of the water-supply there as an 

 illustration of the whole question, the supply used to be obtained from both these sources, 

 the river being the Blue Nile — a mighty stream springing from Lake Tsana in the 

 Abyssinian highlands, and fed for the most part by the torrential rains which fall, at 

 one jjeriod of the year, on the mountains and tableland of the ancient Kingdom of 

 Ethiopia. 



Before, however, entering more minutely into the condition of affairs which obtained 

 and now obtains at Khartoum let us see if there is any recent work to guide us in our 

 consideration of water-supplies in the Tropics, both from a general and from a 

 bacteriological standpoint. As stated, this is not easy to find, but an excellent article 

 on drinking-water in India, and its connection witli the subsoil water, is that bv 

 Lieut. -Col. Dawson''' of the Indian Medical Service. He advocates the preparation of 

 contour maps of the subsoil water and deals with the filtering capacity of soil. One 

 point he specially brings out — and it is one with which I must deal later and w-hich 



