A commonly held assumption in Australia is that rainwater tanks don’t provide significant water savings during drought, however, research has showed that yields from rainwater tanks are more resilient to droughts and climate change, than runoff into dams supplying communities with water.
In a study about the relative efficiency of water supply catchments and rainwater tanks, published by Coombes and Barry (2008), drought was defined as a period where runoff into dams reached critically low levels. These defined periods of drought produce very high reductions in runoff into dams ranging from 41% to 69%. Interestingly, the reduction in yields from rainwater tanks ranged from a much lower 0% to 20%.
These results highlight the potential for rainwater tanks to provide a reliable water supply to help supplement water collected via dams and other sources during droughts. It was also noted that it was important that rainwater tanks also supply water during wetter periods, thereby reducing water demands from other sources during more plentiful years, allowing greater carryover storage of water in dams for use in droughts. Another benefit of using a closed tank system is that there is significantly reduced evaporation loss from a system of this type, compared to open water storage. Investing in water tanks has the potential to improve overall water reliability and will help drought proof your water supply.