Consequences to water suppliers of collecting rainwater on housing estates

摘要

The collection, storage and use of rainwater from roofs reduce the need for potable water.nHowever, if water suppliers are to decrease their infrastructure costs as well as theirnoperational costs (due to water savings), the rainwater system has to provide most of the timena significant percentage of the water demand. This paper adopts the viewpoint of the waternsuppliers and investigates how reliable this source of water is in the case of a housing estate,nconsidering WC flushing as the only water demand. A housing estate was modelled andndifferent realistic input scenarios (water demand for WC flushing, storage capacity, roof area,nand rainfall) were defined. Three indicators were exhibited. The variability generated by eachninput on the indicators was evaluated. The indicators were estimated for 63 homogeneouslyndistributed French cities. Among the indicators exhibited in this paper, the most relevantnone is the percentage of water supplied from the tank that is secured during 95% of thendays of the simulation. The main conclusion is that the optimum way of determiningnthe storage capacity of the rainwater collection system is not the same from the viewpointnof the users than from the viewpoint of the water suppliers. Indeed, water suppliers tendnto require bigger tanks in order to take into account the rainwater collection systems inntheir management plan.