Experimental evaluation of rainwater quality for non-potable applications in the city of São Paulo, Brazil

Abstract

This study summarizes the evaluation of rainwater quality and its potential for non-potable applications in the city of São Paulo, Brazil. An experimental system was installed at the Centro de Técnicas de Construção Civil (Civil Construction Techniques Centre, Escola Politécnica, University of São Paulo) such that analysis of the physical, chemical and bacteriological composition of rainwater—total and faecal coliforms, Clostridium Sulphite-reducer, Enterococcus and Pseudomonas aeruginosa—could be conducted. The need for water treatment was also evaluated in order to match quality to specific uses. Rainwater samples were collected from the roof by an automatic sample collector. Samples were also collected from a rainwater storage tank. In the operation of the system, analysis of rainwater's potential use in non-potable applications, such as flushing toilet bowls, was also conducted. The results obtained did not meet recognised quality standards, leading to the conclusion that water disinfection prior to use is required.

Keywords:

• Rainwater collecting system
• Rainwater quality
• Rainwater utilization
• Water conservation

Acknowledgements

The authors are grateful to Ana Maria Ramalho de Paula, Giselle Ibette Silva Lopez Lopes, Júlia Taeko U. Yoshida and Anita Scorsofava from Adolfo Lutz Institute for their support on rainwater analysis.