Rainwater harvesting for non-potable purposes in residential settings: a case study

Abstract

With the current global population of 8 billion inhabitants on planet Earth, the United Nations Educational, Scientific and Cultural Organization estimates that 2 billion people lack access to clean drinking water. This phenomenon is observed not only in less affluent regions but also in major urban centers, such as Olinda, the first capital of the state of Pernambuco, where water supply issues are frequent, even in a city designated as a UNESCO World Heritage Site. This work aims to present an alternative for the better utilization of water by promoting the harvesting of rainwater for use in activities that do not require potable water, thus favoring the reduction of consumption of potable water resources. The object of the study is a residence located in the Historic Site of Olinda, where water supply is provided on alternate days according to the Pernambuco Sanitation Company (COMPESA). The adopted methodology included the following steps: collecting monthly readings from the water meter, analyzing local rainfall conditions, determining the influential coverage area, assessing the effective consumption of potable water, and evaluating the feasibility of implementing a rainwater harvesting system. As a result, a significant percentage of potable water savings could be identified, and the feasibility of implementing a rainwater harvesting system in the residence was also observed.