Believe it or not, 90% of the wells in Panjim are contaminated, mainly because the distance between septic tank and wells or ground water tanks are less than the minimum 20 mtrs.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/90-wells-panjim-contaminated
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/herald-panjim
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/goa
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/wells
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/groundwater
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/groundwater-pollution