South East Queensland
19.3 Leakage to groundwater
This line item consists of leakage from the urban water supply system (including potable and non-potable water), wastewater collection system and recycled water supply system discharges groundwater within the South East Queensland (SEQ) region.
Leakage data wereonly available for leakage from the potable water supply systems that form part of the SEQ Water Grid and was estimated to be 25,534 ML. Wastewater exfiltration from sewer mains and leakage from recycled water supply systems could not be quantified in a way that is complete, neutral and free from material error. Leakage from potable water supply systems that do not form part of the SEQ Water Grid also could not be quantified in a way that is complete, neutral and free from material error.
Urban utility leakage volumes were calculated by taking the difference between the water diverted from surface water and groundwater, and the water delivered to consumers in the urban utility's portion of the SEQ Water Grid. As the SEQ Water Grid extends outside of the SEQ region, area-based weighting was then used to calculate the leakage volume within the SEQ region.
Assumptions, Limitations, Caveats and Approximations
The method used to estimate potable water supply system assumes that all water delivered to consumers was metered. If consumers exist that are not metered, this would result in an over estimation of the leakage. This overestimate, if present, would be minor in volume.
Leakage estimates from potable water supply systems that do not form part of the SEQ Water Grid could not be quantified. This may have resulted in a slight under estimate of leakage, but due to the small size of the off-grid potable water supply systems, the volume would be minor.
No information on the volume of water lost due to pipe bursts was available. The leakage to groundwater includes a component for pipe bursts as the method employed to calculate leakage could not differentiate bursts from leakage. This may have resulted in a slight over estimate of leakage, but the volume would be minor.
Derived from measured data. Estimated in the range +/– 30%.
This line item was not included in the 2010 Account. The 2010 Account did contain line item 20.2 Leakages from water distribution system, which represented the urban water system decrease, but it did not represent the groundwater store increase. The 2011 Account comparative year has included this volume as both an urban water system decrease and groundwater store increase.