SOUTH AUSTRALIAN WATER SUPPLY. 627 



2.— CHARACTER OF THE SOUTH AUSTRALIAN 

 WATER SUPPLY. 



Bij G. A. GOYDER, F.C.S. 



Having analysed a lar<»e number of" samples taken from the 

 principal sources of the water supply of this colony from 1890 to 

 the present time, principally for the Engineer-in-Chief s Depart- 

 ment, it appeared to me desirable to give some account of these 

 waters chiefly from a chemical point of view. The waters may be 

 divided into three classes, all being surface waters, as most of 

 our deep waters are too saline or in too limited quantity for a large 

 supply — soft waters from the slates and clay lands ; hard waters 

 from the limestone formations; saline waters. The number of 

 soft waters met with here is very limited, the purest organically 

 being that from the Waterfall Gully, which is utilised, as far as 

 possible, to supply Buvnside and Kensington ; an analysis of this 

 water is given in Table 1, under Kensington, and it will be seen 

 that the water is fresh, moderately soft, and organically pure. 

 This soft water in passing through the pipes takes up a little 

 coloring matter from the protecting composition with which they 

 are coated the more so the softer and less saline the water is. 

 This sometimes leads to an idea that the water is impure, but as 

 the coloring matter is inocuous and the quantity present exceed- 

 ingly small, this idea is erroneous. As an example of this the 

 Kensington water of July, 1890, may be quoted. In the Burnside 

 South reservoir this water had a color equal to 0"79 (see ap- 

 pendix); after passing through the pipes the sample drawn at 

 Kensington had a color equal to 2-43, about three times as 

 deep, the organic impurity iu the Avater being less than in the 

 reservoir. Hard waters, after passing through similar pipes, do 

 not take up a trace of color, aad vvhere otherwise pui'e appear 

 of a normal pale blue when seen through a long tube. I do not 

 know of any other case in which we have a soft water organically 

 pure that is utilised, although there may be others, which, being 

 mixed witli an excess of hard water, are not recognisable under this 

 heading. 



There are a number of soft waters obtained from a catchment 

 area of claj land, the Nelshaby and Kapuuda reservoirs being- 

 supplied with water of this description. Generally these waters 

 are so contaminated with organic matter, chiefly vegetable, that they 

 hold a considerable quantity of matter iu suspension, and are both 

 turbid and organically impure, and capable of supporting a large 

 number of infusoria and other forms of life which make them 

 undesirable for drinking pui-poses if not actually dangerous. The 

 comparative degree of organic impurity of the Nelshaby water 

 varied during 1890-1 from 2-99 to 6-32. Since May, 1891, how- 

 ever, the water in the reservoir has been supplemented from the 

 Beetaloo reserA'oir, and the improvement of the water has beeri 

 proportionate to this supplementary supply. 



