According to Amish Shah, co-head (India research), BofAML, around $75 billion have been spent by the central and state governments combined over the last four years on water related projects.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/270-billion-needed-take-piped-water-every-home-over-15-years-bofaml
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/financial-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/drinking-water
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/budget
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/rural-water-supply
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/ganga
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-supply