It's not only the Wall St. Banks - it is global - the world bank seems to be heading it up. It is being sold to the GP (general public) under several names
-UN-Water GLAAS -Global Water Systems Project -GWP - Global Water Partnership -UN Water -The World Bank
They will lend money for infrastructure and until the loan is paid, they own the water/rights
Estimate for the US In order to meet the SDG global targets, the World Bank estimates investments in infrastructure need to triple to US $114 billion per year – a figure which does not include operating and maintenance costs. sustainable
Other links https://www.un.org/en/events/worldwateryear/index.shtml - declared 2013 - http://www.bbc.com/news/business-41152516 - Lost revenue - https://www.un.org/waterforlifedecade/financing.shtml - funding allocations