6 
direct source is in either case the surface drainage from tracts of 
forest land, and necessarily charged with a large proportion of 
vegetable matter, which, by its decomposition, especially in the 
hot season, is a fertile source of organic impurity ; — but this 
applies to all the available sources of supply for the city of 
Brisbane in nearly equal degree. 
The purity of water stored in artificial reservoirs is greatly 
affected by the depth ; shallow water becomes so heated by the 
sun, that aquatic vegetation forms a dense mass wherever the 
depth is less than fourteen feet ; where the depth exceeds 
fourteen feet it is free from weeds, the surface temperature does 
not rise so high, and evaporation is less. 
It is therefore of considerable importance that, in selecting 
sites for reservoirs, the greatest practicable depth should be 
secured ; and it is therefore urged that if reservoirs are formed 
in the valleys of Moggill Creek, the dams should be raised higher 
than that at Enoggera, and that 80 feet would be quite prac- 
ticable. 
In connection with the question of supply, it may be con- 
venient to advert to what seems to be an excessive quantity of 
water consumed in Brisbane. 
In 1871 the lower district of the city consumed about 48 
gallons per head for all purposes, including street watering ; and 
in the upper district 30 gallons per head. At the present time, 
the consumption in the lower district is 50 gallons per head, 
though street watering has been trebled ; but in the upper 
district, where no streets are watered, the consumption has risen 
to 70 gallons per head. 
Now, in the upper district not one-tenth of the houses have 
baths, and the average number of each household is six, and the 
consumption 420 gallons per diem, equal to 200 buckets of 
water, a quantity obviously in excess of what can be used ; and 
the only conclusion which can be arrived at is, that more than 
half the water delivered is allowed to run to waste. 
If, instead of an annual water rate based on the size of the 
house, water "were charged by meter, the consumption would 
probably be reduced below what is conducive to the health of 
the city ; but it is probable that if a regular system of super- 
vision and small fine were imposed for allowing water to run to 
waste, the consumption might be reduced to 30 gallons per 
head, a quantity estimated to be ample for all purposes in 
English towns. 
If the consumption were reduced to 30 gallons, the present 
supply of one million gallons per diem wmuld be sufficient for the 
32,000 persons at present residing in the city and suburbs ; but 
the contingency of a rapidly increasing population demands that 
additional provision should be made for the future, and that, 
under any circumstances, the requisite sites for collecting 
