Can simplified design methods for domestic rainwater harvesting systems produce realistic water-saving and financial predictions?

摘要

Rainwater harvesting systems are a recognised approach for reducing reliance on potable mains supply. Many domestic systems are designed and assessed using simplified approaches that can be applied with little prior information. Oversimplification of the physical processes involved and ad hoc consideration of associated costs means that the results produced by these simplified methods are of questionable accuracy. This paper looks at three popular simplified approaches and compares the predicted water-saving and financial performance with that of a more detailed simulation model, which includes explicit consideration of the physical processes and associated system costs. The simplified approaches predict significantly higher water and financial savings compared with the detailed model. Consequently it is recommended that simplified approaches should not be relied upon and greater preference should be given to the use of more detailed simulations that explicitly consider the important physicalprocesses and include a thorough assessment of costs.