System dynamics evaluation of household water use behavior and associated greenhouse gas emissions and environmental costs: A case study of Taipei city

Taiwan is an island surrounded by sea and only 19 % of its freshwater usage is for domestic applications. A system dynamic model was developed to investigate interactions between household water use behaviors (toilet flushing, clothes washing, bathing/showering, and cleaning) and associated greenhouse gas emissions and environmental costs. Six hundred and fifty face-to-face interviews were conducted in 12 districts of Taipei. The results showed that the respondents’ individual attributes were not significantly related to water use behaviors. The highest volume of water was used for cleaning (27.7 %), followed by clothes washing (26.2 %), bathing/showering (26.1 %), and toilet flushing (20.0 %). Five water management scenarios with 5 %–20 % reductions in water volume from different water use behaviors were simulated. The maximum reduction in water use (6.27 t) was found in the fifth scenario (20 % reduction), which reflected the priority the respondents gave to save water if its price increased. 27.2 % of respondents had water saving appliances; 20.5 % and 16.4 % of the appliances were toilets and shower heads, respectively. The environmental cost of GHG emissions associated with water use behavior was US$0.001/t, causing an 8% increase in water price. A better understanding of household water use behaviors is needed to develop bottom-up strategies or measures for sustainable water management. Water saving measures or strategies would lead to targets being met in a short time.