[dogma1138]

Large scale water cooling systems are open return systems.

Basically they pump in cold water and pump hot water back out.

Cooling the water is expensive and ineffective on large scales.

Beyond that you have evaporative cooling which is used for large scale HVAC systems in this case the water simply evaporates away into the atmosphere.

[m-j-fox]

Fine but why not pump it out onto some crops? Here I am paying to heat water for my house and pool -- I should move next door to Google and hook up to their drain pipe.

[dogma1138]

You can try some places use reclaimed hot water from industrials sources for metropolitan heating.