10.6 Leakage from urban water system
The volume reported (13,962 ML) represents background leakage from the pipes in the recycled water and mains water network. The leakage breakdown is shown in the following table.
|Recycled water main pipes||173|
|Water mains pipes||13,789|
GIS analysis was used to calculate the length of SA Water pipes within the Adelaide region. The leakage volume was calculated by multiplying this length and the 2010–11 mains loss rate for Adelaide, which was 3.52 kL/km/day (National Water Commission 2012).
Assumptions, Limitations, Caveats and Approximations
- Assumes length of water mains based on initial and final length.
- Leakage from bulk transport pipelines (Mannum–Adelaide Pipeline, Murray Bridge–Onkaparinga Pipeline and Swan Reach–Stockwell Pipeline) and wastewater pipelines is assumed to be negligible.
- All leakage is assumed to be to groundwater.
Derived from measured data. Estimated in the range +/– 30% to 50%.
This line item corresponds to line item 15.2.4 Leakage from water distribution system to groundwater reported in the 2010 Account. In the 2011 Account, the following changes were made that caused the 2009–10 year value to be restated:
- In the 2011 Account the Bureau of Meteorology has included a separate irrigation scheme store. This change was made to provide users with clearer information and this means that transactions associated with the irrigation scheme are reported separately to the urban water system.
- An error in the volume reported for potable water and recycled water pipes was identified due to data quality improvement processes.
- In the 2010 Account, the fires services pipe network was included in leakage calculations. This was incorrect because the fire services pipe network does not form part of the urban water system.
Although these changes to the volume reported were small, the volume was restated to correct errors and provide comparability between years. These changes and their respective volumes are detailed in the following table. The restated comparative year volume is 14,259 ML.
|2010 Account line item name||Network||Volume at 30 June 2010 reported in 2010 Account (ML)||Value difference to volume reported due to prior period error correction (ML)||Value difference to volume reported due to reclassification (ML)||Volume at 30 June 2010 reported in 2011 Account* (ML)|
|15.2.4 Leakage from water distribution system to groundwater
||Urban water supply system – pipes||14,135||(48)||14,087|
|Recycled water supply system – pipes||425||(253)||172|
|Irrigation water supply system – pipes||182||(182)||0|
* Recalculated volume is an overestimate as the leakage calculation method used final pipe length for 2009–10. Whereas the leakage calculation method used for 2010–11 assumed that pipes were constructed consistently throughout the year. As a result, the leakage calculation method used the average of the starting and ending pipe length for 2010–11.