Though it is mandatory to install a rainwater harvesting system in any construction over 3,171 sq ft, hardly 10% such buildings in the city have followed the rule.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/ngo-shows-way-harvest-rainwater-small-buildings
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/times-india-nagpur
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/maharashtra
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-harvesting
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/buildings
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ngo
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/nagpur-d
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-resources