“…Surveys indicate that at least 20 % of these systems are malfunctioning; over half of all US septic systems are over 30-yr old (US EPA, 2005). Old and improperly maintained systems are prone to failure and provide inadequate conditions for the effluent treatment processes including physical filtration, surface adsorption, sedimentation, and inactivation of the contaminants in the soil (Canter, 1997;Charles et al, 2005). Leachate from septic systems has been identified as a major potential source of groundwater contamination with nitrate, pharmaceutically active compounds (PhACs), endocrine active substances (EAS), other household chemicals, as well as pathogens such as bacteria, viruses, helminths, and protozoa (Perkins, 1984;US EPA, 1998, 2002aGerba and James, 2005;Carroll et al, 2006;Fong et al, 2007;Stanford et al, 2010).…”