Canada's water resources outlook, afflicted by an ever increasing demand, compounded with increased pollution and climate change effects, has been a harsh awakening for researchers and practitioners, currently searching for sustainable water systems. Joining this initiative, this thesis evaluates life cycle-based energy use and GHG emissions of pursuing an integrated demand management strategy in the City of Toronto residential sector. This alternative solution combines efficient plumbing with the utilization of rainwater to supplement municipal supply for toilet and outdoor purposes.A holistic characterization of how the implementation of the proposed water supply system leads to energy savings and GHGs reduction is facilitated by the whole-system approach, which allows an assessment of environmental metrics to be complemented with system's hydraulic performance analysis. The study shows how the simplicity of home storage can act both as a hedge against climate change and a means of stretching tight infrastructure budgets.