3.1 Urban water supply system
The volume reported in the water accounting statements (904 ML) refers to the volume of water held in ACTEW's potable and non-potable water supply system on 30 June 2012. There are 47 tanks (service reservoirs) within ACTEW's supply system and approximately 3,140 km of pipes.
This volume is expected to remain relatively constant each year, with slight increases in pipe network volume due to the expansion of the network, and slight changes in the tank (service reservoir) volumes due to operational level changes.
The volume in the tanks (service reservoirs) was reported as the volume at 8 am 1 July 2011 and 1 July 2012. The volume in the pipe network was calculated based on the pipe lengths and nominal internal pipe diameters as recorded in the GIS database, assuming all the pipes were full. This includes both non-potable and potable water pipes.
Assumptions, limitations, caveats and approximations
These data does not include service water storages or the pipe network managed and owned by QCC. The QCC water supply system is much smaller in size than the ACTEW system and it is expected that the volume stored within the QCC tanks and pipes would be much less than that reported for ACTEW's system.
Data are measured; uncertainty is estimated at +/– 10%.