Water being a good solvent, is prone to physico chemical and microbial contamination. Municipal sewage, both treated and untreated is often released into the receiving water bodies, which influence water quality.
Links:
[1] http://admin.indiaenvironmentportal.org.in/feature-article/coliform-mpn-counts-municipal-raw-sewage-and-sewage-treatment-plant-relation-water
[2] http://admin.indiaenvironmentportal.org.in/category/author/yudhistra-kumar
[3] http://admin.indiaenvironmentportal.org.in/category/author/m-vikram-reddy
[4] http://admin.indiaenvironmentportal.org.in/category/journal/journal-environmental-science-engineering
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-pollution
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewage-pollution
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewage-treatment-plants-stp
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/micro-organisms
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/india
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/tamil-nadu
[11] http://admin.indiaenvironmentportal.org.in/category/thesaurus/kanchipuram-d