Art. VIII. — Six Months Daily Examination of 

 Melbourne Tap Water. 



By THOMAS CHERRY, M.D., M.S., 



Lecturer in Bacteriology, The University of Melbourne, Bacteriologist 

 to the Department of Agriculture. 



[Eead 8th May, 1902.] 



Before giving the results of the examinations of the Melbourne 

 Water Supply, a short description of the sources of the water and 

 of the reticulation is necessary in order to explain the results 

 obtained. 



Melbourne is probably unique among the large cities of the world 

 in being supplied with water which comes from uninhabited catch- 

 ment areas. The water supply consists of two systems — the Yan 

 Yean and the Maroondah. The Yan Yean system collects the water 

 from the northern slopes of the Dividing Range in the neighbour- 

 hood of Mount Disappointment, about 30 miles north of the city. 

 This catchment comprises 26,500 acres. The most distant source 

 is the Silver Creek, the water of which is conveyed in an open 

 aqueduct, 8 miles long, to the Wallaby Creek Weir. From 

 this point the combined waters of the Wallaby and Silver Creeks 

 are conveyed by a similar aqueduct for 5 miles to the southern 

 crest of the Dividing Range, at a height of 1700 feet above sea 

 level. The water is then dropped by a series of cascades into the 

 bed of Jack's Creek, one of the branches of the Plenty River. 

 Jack's Creek leads to Toorourong Reservoir, with a storage 

 capacity of 60 million gallons, whence a clear water channel 

 nearly 5 miles long leads to the Yan Yean Reservoir. The 

 average flow from Silver Creek is five, and from Wallaby Creek 

 seven million gallons a day. 



The Yan Yean Reservoir is 600 feet above sea level. It 

 covers an area of 1360 acres, with an available depth of 18 feet, 

 and a storage capacity of 6400 million gallons. The face of the 

 embankment and a considera.ble extent of the shores of the 

 reservoir have been pitched in order to prevent discolouring of 



