There is a case study for the city of Liverpool in the UK attached for information Dagani. More useful information can be obtained from http://www.gdrc.org/uem/footprints/ 

Regards, John

Check "citing article" on the right section of the page of the following link, I reckon there is a related study.

http://www.sciencedirect.com/science/article/pii/S0959652615006873

Hi Rao, 

Please find the below links for additional information 

Urban Water Footprint: an innovative approach to manage water in urban areas

Urban Water Footprint: a new approach for water management in urban areas  

http://www.urban-wftp.eu/en/project/what-is-the-water-footprint/,13

http://waterfootprint.org/en/about-us/events/urban-water-footprint-innovative-approach-manage-w/

http://enerea.hu/esemenyek/Urban_4_A_K_Chapagain.pdf

Definitely, you can apply WFA for a city. recently we have concluded the WFA study fro Delhi-NCR at NIH including all three major sectors (i.e. Agri. Domestic and Industrial) for Blue, green and grey component. We have also considered the floating population as well as virtual water import and exports in form of commodities. 

Rgds

Nema