Impact assessment of on-site sanitation system on the quality of groundwater in sandysoil of periurban area of Bangalore City, Karnataka, India - A case study

Due to inadequate sanitation and practice of onsite sanitation like pit latrines and septic tanks in Periurban areas, the contaminant levels are exceeding permissiblelevels in ground water drinking sources resulting in water borne diseases, causing widespread morbidity and mortality.Contamination of groundwater sources by pathogenic bacteria and nitrate are two major public health risks due to-onsite sanitation systems. A field study was carried out for two year in a peri urban area of Bangalore-rural district. During the study bore well water samples were collected at eleven sampling stations near onsite sanitation systems.The collected bore well water samples were analysed for critical onsite-parameters and analysis of bore well water samples indicates that groundwateris unfit for drinking-purpose. Higher concentration of nitrates and chlorides in bore well water samples show that ground water is getting contaminated with onsite sanitation. The regression graphs are plotted to study variation of nitrate and total count, with depth, distance and years of usage. The regressiongraphs indicatethat-the 10m distance between public borewell and septic tank is sufficient to prevent groundwater contamination for present days. Appropriate legislation on zoning, specification, siting, designing, construction and maintenance of onsite sanitation system are necessary to protect groundwater aquifers in future.