Journal of Water and Health Vol 5 No 1 pp 129–148 © IWA Publishing 2007 doi:10.2166/wh.2006.054
Unsafe tap water in households supplied from groundwater in the Salento Region of Southern Italy
Costantino Masciopinto, Rosanna La Mantia, Annalaura Carducci, Beatrice Casini, Agata Calvario and Edoardo Jatta
Consiglio Nazionale delle Ricerche, Istituto di Ricerca sulle Acque, Reparto di Chimica e Tecnologia delle Acque, via Francesco De Blasio, 570123, Bari, Italy Tel.: 0039-080-5829537 Fax: 0039-080-5313365 costantino.masciopinto@ba.irsa.cnr.it
Dipartimento di Patologia Sperimentale, Biotecnologie Mediche, Infettivologia ed Epimediologia (BMIE), via S. Zeno 35-39Pisa, Italy
Dipartimento Medicina Interna e Medicina Preventiva (DIMIMP), piazza Giulio Cesare, 1Bari, Italy
ABSTRACT
Although the fractured aquifer of the Salento supplies over 80% of the drinking water requirements of the local population, its exposure to pollution has recently increased. In recent years, owing to the arid climate and droughts, the spreading of wastewater on soil for irrigation has become much more frequent. Consequently, hazardous and pathogenic microorganisms released with wastewater have been transported into the subsoil and have contaminated groundwater. An elaboration of epidemiological data has shown that the local population has the highest exposure to endemic gastroenteritis in Italy. In order to reduce human exposure to unsafe groundwater, the setback distance for drinking wells necessary to achieve the ‘natural disinfection’ criteria, has been determined experimentally at the Nardò aquifer (Salento region), supported by groundwater monitoring results and a mathematical transport model able to determine the apparent pathogenic microorganism pathways in fractures. The results also provided valuable inactivation constants of cultural indicators (coliforms, enterococci, Clostridium spores and somatic coliphages) and viruses in the wastewater that have been injected into the fractured aquifer since 1991. Furthermore, the efficacy of chlorine to remove viral indicators from water in a well 500 m from wastewater injection was tested. Hypochlorination reduces somatic coliphages and Clostridium spores in groundwaters but did not achieve complete inactivation in all tests. Complete disinfection of groundwater samples was possible only when there was an initial Clostridium spores count of  10 CFU 100 ml-1.
Keywords: natural water quality; pathogenic microorganisms detection; pathogens inactivation constants; waterborne disease outbreaks
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