According to the Delhi Jal Board, creation of district metering areas will be crucial to the decision.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/delhi-jal-board-set-hire-consultant-%E2%80%98exploring-possibility-24%C3%977-water-supply%E2%80%99
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/indian-express-new-delhi
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-supply
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/delhi-jal-board-djb
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/national-envirnmental-engineering-research-institute-neeri
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/drinking-water