Retention Performance of Domestic Rain Water Harvesting Tank under Climate Change Conditions

The goal of this paper is to investigate the efficiency of domestic Rain Water Harvesting (RWH) tank to reduce the inflow discharge to stormwater sewer systems, which intends to be an option to increase urban resilience to climate change impacts. A dimensionless methodology developed based on a water balance model at daily temporal scale was applied to determine both the obtainable water saving due to the use of rain water for toilet flushing (i.e. reduce the use of portable water) and meanwhile reduce stormwater volumes discharging to sewer systems by the tank storage. The methodology and a RWH tank system was evaluated applying the daily rainfall data obtained in two met-stations of Blindern in Oslo and Rygge in Fredrikstad, South Norway. Results show, for all the considered scenarios in the two case studies that the use of the rainwater storage tank can provide significant reduction of water volume discharges to the storm water sewer, accordingly the resulting damages during the extreme events will be reduced.