Adelaide
20.3 Leakage to groundwater

The volume reported in the water accounting statement (33 ML) represents background leakage from the pipes in the irrigation water supply system to groundwater.

Only leakage from the Barossa Infrastructure Limited (BIL) scheme was quantified. This value corresponds to less than 1% leakage of the total water supplied to the irrigation scheme. The BIL Annual Report 2012 reported that due to the installation of more accurate electronic meters for most large customers, the losses in the system were reduced to 1.3 % during the 2011–12 year.

Data regarding leakage were not available for the Virginia Pipeline Scheme. This volume is assumed to be small, and its omission is unlikely to have a material impact on the irrigation scheme balance.

Leakage from the Willunga Water Basin Company pipes was assumed to be negligible. Numerous pressure monitoring sites will rapidly identify leaks and leaks are fixed quickly.

BIL: data for calculation of the leakage value.

The leakage from BIL's irrigation scheme (33 ML) was derived from the difference between water supplied to the irrigation scheme and water delivered to the customers:

• The area serviced by BIL extends beyond the boundary of the Adelaide region. It was assumed that the length of BIL infrastructure outside the Adelaide region is insignificant.
• It was assumed that the difference between water supplied to the irrigation scheme and water delivered to the customers represented leakage from BIL infrastructure.

The uncertainty estimate was not quantified. However, the leakage rate calculated (less than 1%) is close to the loss rate of 1.3% reported in (Barossa 2012). A significant uncertainty in the calculation is due to metering errors, in particular for customers' meters that are read in October, December, April and September as their water year extends from 1 October to 30 September.