Hello Kaustubh, I liked the ...

Hello Kaustubh,

I liked the answer offered by Dave Johnstone , very much reflecting my own thinking. I'd point you additionally  here.

Most of the water cooling usually used in IT are close circuits employed in cooling of IT equipment. I doubt one would tap water and run it through heat exchangers and then spill it out. You may average that water consumption eventually. 

Water consumption is usually statistically published.  You may want to see this. It varies tremendously from country to country.

If your company provide to the stuff more than tap water, you may consider in estimating daily shower consumption, daily dishwasher water use, etc. I'd give a better rule: estimate amount of  wastewater your company would generate in order to deliver a product, or to exist. 

Think of drinking water, wash water, toilet flushing, give a first estimation and hit a spreadsheet of your own estimation :) 

Good Luck!