Approaching water sensitve cities with adaptive rainwater diversion

Total water cycle management (TWCM) discussion mostly limits the role of residential rainwater harvesting to providing an alternate water supply to a fraction of fit-for-purpose end uses. However, with operational improvements, greater outcomes can be achieved. By increasing the portion of roof area connected and developing adaptive rainwater diversion (ARD), reliable stormwater management outcomes can also be achieved. ARD controls tank drawdown by adapting to changesin dwelling consumption and rainfall, thus allowing the available storage to mimic the pre-urbanised catchment storage recovery. The ARD approach has the basis that mains water savings can be achieved in two ways: 1) Rainwater supply - where the rainwater harvest is used directly to reduce mains consumption of that dwelling; and 2) Rainwater diversion - where rainwater is diverted from the dwelling. This does not directly reduce mains consumption of the dwelling but produces a waterresource that is used by others to reduce mains consumption. In this way, total rainwater yield and mains water savings is the sum of rainwater supply and diversion. This research investigates rainwater supply, rainwater diversion, runoff volume and runoff flow frequency for South East Queensland. Results show, the average sized detached dwelling when fitted with a 5 kL tank and ARD system is compliant with the mandated water saving targets and the Queensland Best PracticesEnvironmental Management Guidelines for stormwater flow frequency management.