This line item refers to the total water used for the irrigation of household lawns and gardens within the Perth region.
Water Corporation: Operational Data Storage System.
Water Corporation.
The amount of potable water used for outdoor use is calculated as a percentage of the total water supply, based on the Perth Residential Water Use Study 2008-2009 (Water Corporation, 2009). According to this study, approximately 39% of the total public water supply is used for outdoor use.
The total water supply (and outdoor water use) is calculated according to the table below.
| 
 | 
 | Volume (ML) | 
|---|---|---|
| 
 | 14.7.2.4 Surface water diversion | 141,285 | 
| Plus | 16.5.3.4 Groundwater diversion | 120,828 | 
| Plus | 19.5.1 Desalinated water supply | 47,693 | 
| 
 | Total water abstracted | 309,806 | 
| Less | 13.8 Internal transfers | 45,233 | 
| Less | Riparian releases | 4,818 | 
| Less | Leakage to groundwater | 11,909 | 
| Less | Operation losses | 893 | 
| 
 | Total water supplied | 246,953 | 
| 
 | Total outdoor use | 96,312 | 
Expected error for water meters is +/- 5%.
The Department of Water requires that all water meters, when tested in situ conditions, must be within 5% accuracy across the full flow rate range (Department of Water 2009).
Actual outdoor water use is not measured. The value reported here is an estimate only.