Water quality and microbial diversity in cisterns from semiarid areas in Brazil Fellipe Alves, Thorsten Köchling, Julio Luz, Sylvana Melo Santos and Savia Gavazza ABSTRACT Harvesting rainwater is a common practice worldwide, particularly in areas with no access to a public water supply or insufficient groundwater reserves. More than two million people living in semiarid regions of Brazil consume rainwater stored in cisterns, and little information is available regarding the water quality. Despite the initial good quality of the rainwater, its harvest and storage can introduce contaminants that must be eliminated before consumption. To evaluate the influence of handling, cistern age and precipitation on the quality of harvested rainwater, we monitored seven cisterns in the semiarid Brazilian Northeast over 4 years. Microbial and physicochemical parameters were monitored once a month, and denaturant gradient gel electrophoresis (DGGE) was performed at the end of the monitoring period. Coliform bacteria were detected in 100% of samples, while Escherichia coli were observed in 73.8%. The alkalinity and conductivity were the highest for the recently built cisterns due to the dissolution of construction materials. The DGGE of the 16S r DNA did not reveal the presence of E. coli. Instead, DGGE bands sequencing indicated that species primarily affiliated with Alphaproteobacteria were present in all cisterns, indicating the presence of microbial ecosystems capable of purifying and stabilizing the stored rainwater. Fellipe Alves Sylvana Melo Santos Savia Gavazza (corresponding author) Laboratory of Environmental Engineering, Academic Center of the Agreste, Federal University of Pernambuco. Rodovia BR-104, Km 62, Nova Caruaru. Caruaru – PE, Brazil. CEP: 55002-970 E-mail: savia@ufpe.br Thorsten Köchling Julio Luz Laboratory of Environmental Sanitation, Department of Civil Engineering, Federal University of Pernambuco. Av. AcadêmicoHélio Ramos, s/n. CidadeUniversitária. Recife – PE, Brazil. CEP: 50740-530 Key words | cisterns, first flush, microbial diversity, PCR-DGGE, rainwater quality, semiarid ABBREVIATIONS CFU colony-forming units DGGE denaturant gradient gel electrophoresis HDPE high density polyethylene NTU nephelometric turbidity units PCR polymerase chain reaction TDS total dissolved solids INTRODUCTION Water scarcity is a problem that affects approximately 1.2 billion people on every continent; over 500 million more people are approaching this status. Another 1.6 billion people, accounting for almost one-quarter of the world population, face economic water shortage: countries lack the necessary infrastructure to move water from rivers and aquifers (FAO ). In Brazil, the geographical distribution of water is not uniform. The Brazilian semiarid region has suffered from a lack of water for many years (Simões et al. ); it is charac- terized by an average annual rainfall of below 800 mm, an aridity index less than or equal to 0.5 (between 1961 and 1990), and a drought risk above 60% (between 1970 and 1990) (Ministry of National Integration ). Because the rainfall only occurs during 3–4 months of the year, there are over a million homes without any source of water during the dry period, which begins 4 months after the end of the rainy season (Ministry of National Integration ). Pesqueira and Caruaru, the towns studied in the present work, are both in northeastern Brazil; the conditions in 513 © IWA Publishing 2014 Journal of Water and Health | 12.3 | 2014 doi: 10.2166/wh.2014.139 Downloaded from http://iwaponline.com/jwh/article-pdf/12/3/513/395725/513.pdf by guest on 19 October 2022