South East Queensland
19.2 Leakage to landscape

Supporting Information

This line item consists of urban water supply system (including potable and non-potable water), recycled water supply system pipe bursts, and wastewater collection system overflows or spills.

No information on urban water supply or recycled water supply bursts was available from the urban utilities.

The volume of wastewater collection system overflows could only be quantified for Unitywater, with the number of spills available for Unitywater, Allconnex Water and Queensland Urban Utilities.

Volume and number of wastewater collection system overflows
Urban utility Spill volume
Number of spill events
Allconnex Water                   590
Queensland Urban Utilities                   626
Unitywater        747                   412
Total SEQ region        747                1,628


  1. The spill volume provided by Unitywater consists of wastewater that has undergone primary treatment.
  2. Spill volume was not available from Allconnex Water or Queensland Urban Utilities.

Quantification Approach

Data Source

Qldwater Statewide Water Information Management (SWIM) system indicator AS36 (number of spills). Unitywater database (spill volume).

Provided by

Bureau of Meteorology.


The number of overflows from the wastewater collections systems for each urban utility were obtained from the Qldwater SWIM system indicator AS36.

Daily overflow data were provided by Unitywater for each wastewater treatment plant. The wastewater treatment plants within the South East Queensland (SEQ) region were selected and the spill volume summed for the entire SEQ region.

Assumptions, Limitations, Caveats and Approximations

The lack of spill volumes for Allconnex Water and Queensland Urban Utilities has resulted in a significant underestimate of the spill volume. Due to the population serviced and proportion of the service area of these utilities being greater than Unitywater, it would be expected that the spill volume from each would be larger than the volume reported for the proportion of Unitywater's service area within the SEQ region.

The lack of urban and recycled water supply system burst data has resulted in an underestimate of the total leakage to landscape. As no data were available on the volume involved, an estimate of the magnitude compared to wastewater spills could not be quantified.

Uncertainty Information

The uncertainty estimate was not quantified.

Comparative year

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 an urban water system decrease due to leakage. The 2011 Account considers this to be leakage to groundwater and has been included in line item 19.3 Leakage to groundwater. No data were available on bursts or spills for the 2009–10 year and as such, line item 19.2 Leakage to landscape has the comparative year reported as dash.