Of all the clean water that our cities consume, roughly half of it flows down our sewers to sewage treatment plants where it is treated and released back to the environment.
Links:
[1] http://admin.indiaenvironmentportal.org.in/news/us-south-africa-and-australia-are-turning-wastewater-drinking-water
[2] http://admin.indiaenvironmentportal.org.in/category/newspaper/guardian-uk
[3] http://admin.indiaenvironmentportal.org.in/category/thesaurus/drinking-water
[4] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewage-treatment-plants-stp
[5] http://admin.indiaenvironmentportal.org.in/category/thesaurus/sewers
[6] http://admin.indiaenvironmentportal.org.in/category/thesaurus/water-supply
[7] http://admin.indiaenvironmentportal.org.in/category/thesaurus/drinking-water-quality
[8] http://admin.indiaenvironmentportal.org.in/category/thesaurus/australia
[9] http://admin.indiaenvironmentportal.org.in/category/thesaurus/united-states-america-us
[10] http://admin.indiaenvironmentportal.org.in/category/thesaurus/south-africa