Systems using rain water or reducing water consumption have been recently developed as an alternative to conventional toilet flushing. This article aims to quantify the environmental impacts of these systems and to identify key factors in each system. A Life Cycle Assessment (LCA) has been carried out to reach these goals.
Scenarios with conventional water supplies present a lower energy requirement and lower environmental loads than recuperation scenarios. Sensitivity analyses indicate that recuperation is energetically favourable only when the energy required for the water supply is higher than 0.8 kWh/m3;, assuming a complex drinking water treatment. The study also reveals that low-flow toilets should be promoted as they lead to significant reductions in energy consumption and in pollutant emissions. A combination of a conventional water supply and low water consumption (scenario CONVeco) is advantageous for all environmental problems.