3.1 Urban water supply system

Supporting information

The opening balance (1,412 ML) and closing balance (1,414 ML) for the urban water supply system included water held in pipes and tanks that make up SA Water's potable water supply system.

For more information on the urban water supply system in the Adelaide region, refer to the Other water resources and systems section of the 'Contextual information'.

Major pipelines used to transfer River Murray water into the region are included in the calculation of the pipes volume.

The following table presents the volume of urban water held, and is itemised by pipes and tanks. 

Urban water supply system volumes at the start and end of the 2011–12 year
Urban water supply system Storage volume at 30 June 2012 (ML)

Storage volume at 30 June 2011 (ML)

Pipes 630


Balancing tanks 616


Process tanks 168


Total 1,414


Quantification approach

Data source

Geographic Information System (GIS) database, storage tank register, and Maximo system.

Provided by

SA Water.


GIS analysis was used to identify potable water tanks and pipes within the Adelaide region. The volume of water in these tanks and pipes is estimated from their total capacity.

The volumes of water held in tanks were collected from SA Water's storage tank register and Maximo system.

The volumes of water held in pipes were estimated from pipe lengths and nominal diameters (stored in the Maximo system) using the following formula:

π  x (D/2) x (D/2) x PL

D = Nominal diameter of the pipe

PL = Pipe length.

Some tanks did not have volumes recorded in the database (< 5%). Queries with key staff obtained these volumes.


Assumptions, limitations, caveats and approximations

  • Process tanks and pipes are assumed to be 100% full in winter, while balancing tanks were assumed to be 50% full.
  • Pipes without recorded construction dates are assumed to have been constructed before the 2011–12 year. It is assumed that all tanks without construction dates were constructed before the 2011–12 year.
  • Only tank and pipe assets that are owned by SA Water are included in the calculation.
  • Nominal diameters of pipes were used to calculate volumes.
  • Fire service mains pipe assets are not included; however the volume was negligible (<1 ML).

Uncertainty information

The uncertainty estimate was not quantified.

Comparative year

In the 2011 Account, storages used for urban water supply only (located off-stream and which harvested only minimal catchment runoff) were reported at line item 3.1 'Urban water system'. These storages were Barossa Reservoir, Happy Valley Reservoir, Hope Valley Reservoir and Onkaparinga Summit Reservoir.

In the 2012 Account, these storages were reported at line item 1.1 Storages in order to be consistent with the classification of storages applied to the other regions of the National Water Account. As a consequence, the 2010–11 volume was restated as per the following table.

Restatement of comparative year information for line item 3.1 Urban water supply
Storage name

2012 Account volume at 30 June 2011 (ML)

2011 Account volume at 30 June 2011 (ML)

Additional information

Barossa Reservoir




Happy Valley Reservoir




Hope Valley Reservoir




Onkaparinga Summit Reservoir







Balancing tanks 616 616  
Process tanks