Modelling for economic cost and environmental analysis of rainwater harvesting systems

As a result of the integration of different methodological tools (life cycle assessment and dynamics simulation) and studies to evaluate the economic cost and the potential environmental impact of alternative water supplies (rainwater and greywater) for urban use, the software program Plugrisost (pluvials, greys and sustainability) has been developed. This modelling tool aims to contribute to urban water planning for smart city development. Plugrisost is a simulation model that facilitates the evaluation of rainwater harvesting (RWH) and greywater systems at different scales of urban planning. It is the only tool known thus far to integrate structural elements such as the sizing of storage tanks, estimated cost and quantitative environmental analysis. Plugrisost can be an adequate tool in the design stage because it provides environmental and economic information related to rainwater tank sizing and its estimates are more conservative than those of other tools. Plugrisost contributes to the design of urban infrastructure of low environmental impact, such as infrastructure that incorporates the use of rainwater, and the self-sufficiency analysis of water in cities. Using Plugrisost, we have found that on the single-house scale, the economic viability of an RWH system would be possible if the price of water is greater than 4 Euros/m3; and the environmental analysis would be favourable to tanks with less than 5 m3 of storage capacity. On the apartment-building scale, the results are 1.4 Euros/m3 and 33 m3, respectively.