South East Queensland
11.7 Stormwater ingress

Supporting information

This line item represents the ingress of stormwater into the urban water system, but the volume could not be quantified in a way that is complete, neutral and free from material error due to the lack of both data and a suitable quantification approach. As urban water supply systems and recycled water supply systems are typically pressurised, it would be expected that little stormwater ingress (entry) into these systems occurs.

Wastewater collection systems consist of gravity sewers and pumping mains. Stormwater ingress into the gravity sewers may occur where illegal connections, flooding or leakage occur.

Stormwater ingress into wastewater collection systems could not be quantified in a way that is complete, neutral, and free from material error in the South East Queensland region as data were not available from the urban utilities. Line item 11.4 Wastewater collected was developed from wastewater treatment plant inflow data and as such includes a component that would be due to stormwater ingress. Stormwater ingress has been included as an inflow to the urban water system through line item 11.4 'Wastewater collected'. In the future, with advances in groundwater infiltration and stormwater ingress modelling it may be possible to separate line item 11.4 'Wastewater collected' into groundwater infiltration, stormwater ingress, and wastewater collected.

The inclusion of stormwater ingress in line item 11.4 'Wastewater collected' and omission of line item 11.7 'Stormwater ingress' is not considered to be material to the water balance for the urban water system store.