Treatment MeasuresRain Water Tanks : Treatment Performance
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To maximise the stormwater treatment opportunity that rainwater tanks provide, tanks need to be plumbed to a consistent year round water use such as toilet flushing.
The curves below show pollutant removal performance expected for rainwater tanks plumbed to toilet systems for different tank size, roof area and occupancy levels. These curves are based on the Melbourne hydrological region and it is expected that different hydrological regions will result in varying treatment performances. The size of the treatment measure can be simply adjusted to ensure suitable performance in other regions throughout greater Victoria. These adjustment factors are provided in Chapter 2 of the WSUD Engineering Procedures (PDF 691kb).
These curves are the basis to the STORM tool, a web based system for assessing the performance relative to best practice objectives for TN.
The curves were derived using the Model for Urban Stormwater Improvement Conceptualisation (MUSIC) (Cooperative Research centre for Catchment Hydrology 2003).
The curves were derived assuming the systems receive direct runoff (ie no pre-treatment) and have the following characteristics:
| Treatment Measure | Values used in Music 3.0 |
|---|---|
| Rainwater Tanks were modelled using the following parameters: | |
| Rainwater Tanks | The amount of reuse was based on the number of people in the house and the standard reuse rate of 20 L/person/day.
k (TSS) =400, k (TP) =300, k (TN) = 40C* (TSS) =12, C* (TP) =0.13, C* (TN) = 1.4 |