The environmental impact of household's water use: A case study in Flanders assessing various water sources, production methods and consumption patterns.

Responsible water use and sustainable consumption and production are high on the agenda of multiple stakeholders. Different water supply sources are available, including tap water, bottled water, domestically harvested rainwater and domestically abstracted groundwater. The extent to which each of these water supply sources is used, differs over consumption patterns in various housing types, being detached houses, semi-detached houses, terraced houses and apartments. To identify the environmental impact of a household's water use and potential environmental impact reduction strategies, a holistic assessment is required. In this paper, the environmental impact of a household's water use in Flanders (Belgium) was assessed including four different water supply sources and four different consumption patterns by means of a life cycle assessment. The outcomes of this study reveal a large difference between the environmental impact of bottled water use, having a global warming impact of 259 kg CO2-eq.·m-3, compared to the other three supply sources. Tap water supply had the lowest global warming impact (0.17 kg CO2-eq.·m-3) and resource footprint (6.51 MJex·m-3) of all water supply sources. The most efficient strategy to reduce the environmental impact of household's water use is to shift the water consumption from bottled to tap water consumption. This would induce a reduction in global warming impact of the water use of an inhabitant in Flanders by on average 80%, saving 0.1 kg CO2-eq.·day-1 in case of groundwater-based tap water. These results provide insights into sustainable water use for multiple consumption patterns and can be used to better frame the environmental benefits of tap water use.