THE SYDNEY WATER SUPPLY. 215 



Prospect Reservoir, which it is unnecessary to dilate upon, 

 beyond stating that, as a consequence, no reliance can be 

 placed on what previously was regarded as a reserve 

 storage in that reservoir, namely, the 5,000 million gallons 

 below the gravitation limit. 



In my opinion, we should in future make every endeav- 

 our to work up and permanently maintain (if I may be 

 permitted to so express myself) a reserve storage of not 

 less than 600 days, equalling 1.64 years. Indeed, it would 

 be wiser to make it considerably more than this. That it 

 can be done without making any appreciable strain upon 

 the ratepayers will be shown presently. 



In 1921, assuming that the Cordeaux is then completed, 

 the population at 4 per cent, increase will have reached 

 1,112,000 people, consuming, say, 52 gallons daily per head, 

 the daily consumption will amount to 57,821,000, and, as- 

 suming losses from evaporation, etc., to amount to 15 mil- 

 lion gallons daily from the three reservoirs, the total daily 

 loss will amount to 72,821,000, which would result in a re- 

 serve storage capacity of 587 days, or 1.61 years, which it 

 will be observed is less than the reserve I have suggested. 

 Assuming that it will take four years to provide further 

 storage elsewhere, by 1924 the consumption and evapora- 

 tion will have amounted to 87,546,000, and the reserve 

 storage under the most favourable conditions will have de- 

 creased to 488 days' supply, equalling 1.33 years, or actu- 

 ally less than the reserve storage at the present time (in 

 May, 1917), when we are just starting to build the Cor- 

 deaux Dam. 



In 1925 the new storage reservoirs should be ready to take 

 up the duty. I have not yet mentioned where they should 

 be located, but presumably the Avon would be one. It 

 would have a catchment area of 63 square miles, or 13 



