Economic evaluation of stormwater harvesting : a case study

Harvesting Stormwater is gaining importance as it is viewed as a potential alternative source for meeting non-potable water demand from consumers. However, there have not been many economic studies carried out on the cost of supplying stormwater to consumers. The study reported in this paper makes an effort to estimate the cost of supplying stormwater to consumers using a case study from Gosford Local Government Area (GLGA). A significant finding of this study is that the larger urbanised catchments are the most suitable locations for stormwater harvesting projects. The results obtained indicated that the cost of supplying treated stormwater for non-potable purposes varied between $3/kL and $5/kL, which is significantly higher than the cost of town water supply. In depth analyses revealed that the major component of the capital cost is attributed to the cost of distribution system. Therefore, in areas that are already serviced by dual reticulation, it is possible that the cost of supplying stormwater would be equal to or lower than that of the existing town water supply. In addition, further refinement of cost functions can lead to more realistic $/kL values for the water harvested from stormwater.