19.3 Urban water system leakage to groundwater
a. Leakage to groundwater
The volume reported (16,529 ML) represents leakage from Adelaide's mains water network to groundwater during the 2012–13 year. This includes real losses from background leakage and pipe bursts as it was not possible to separate these two volumes.
b. Urban water system overview
The urban water supply system is one of three subcomponents of Adelaide's urban water system. The three subcomponents are the:
- urban water supply system
- wastewater system
- recycled water system.
During the 2012–13 year, Adelaide's urban water supply system relied on three important water sources. Imported River Murray water (line item 11.9 Delivery of water to urban water system under inter-region agreement) and surface water harvested from catchments within the Adelaide region (line item 11.12 Entitled diversion of allocated surface water to urban water system) made up the majority of the water sourced for urban supply; 42% and 35% respectively. Desalinated water (line item 11.6 Delivery of desalinated water to urban water system) made up the remaining 23% of inflows to the urban water supply system in the Adelaide region.
Potable water consumption within the region (line item 19.4 Delivery to urban water system users) was 137,028 ML during the 2012–13 year, representing 86% of all outflows from the urban water supply system. Smaller volumes of potable water were discharged to South Para Reservoir (line item 19.5 Discharge from urban water system to surface water: 2% of outflows) and transferred out of the region via normal operations in SA Water's service area (line item 19.11 Transfer of water outside region: 3% of outflows). Leakage from the water mains (line item 19.3 urban water system leakage to groundwater: 10%) made up the remaining urban water supply system outflows.
The following figure shows all the inflows and outflows for the urban water supply system. For more detail on a particular flow associated with the urban water supply system, refer to the line item notes. A misbalance of 2,140 ML or 1.3% was calculated for the urban water supply system. This misbalance may be due to a number of factors such as metering inaccuracies, unaccounted losses and inaccuracies in the estimation of certain volumes.
Schematic diagram of water inflows and outflows for Adelaide's urban water supply system during the 2012–13 year; line item numbers are provided in brackets
Geographic Information System (GIS) database; unpublished National Performance Report (NPR) data.
GIS analysis was used to calculate the length of SA Water mains pipes within the Adelaide region. The infrastructure leakage index, which was 4.2 kL/km/day (SA Water's unpublished NPR data), was multiplied by this pipe length to obtain the 2012–13 leakage volume for Adelaide,
Assumptions, limitations, caveats and approximations
- It was assumed that pipe length, used to calculate the leakage volume, remained unchanged in the 2012–13 year, compared to the 2011–12 year.
- Assumes the volume reported represents both pipe bursts and background leakage (real losses) and, because it was not possible to separate the two components, the total volume is assumed as leakage to groundwater.
- Leakage from bulk transport pipelines (Mannum–Adelaide Pipeline, Murray Bridge–Onkaparinga Pipeline and Swan Reach–Stockwell Pipeline), wastewater pipelines, fire services and recycled water pipes were not quantified.
Derived from measured data. Estimated in the range +/– 30% to +/– 50%.