They dump it because it's not cool anymore and nobody is wanting to buy hot water from them at a cost that makes it worth their while.

If they had the capability to cool the water fast enough then they'd use a closed loop cooling system and wouldn't need to pump fresh, cool groundwater.

Well, duh. If I had to pay nothing for water, I would also just run the tap through a radiator all day and save on the AC electricity.

But then I also have a conscience and realize what a gigantic waste that is, so I don't.

This is basically how we cool our house in Montana during the summers. Cold water is pumped up one well and hot water is returned down another well. It uses much less electricity than a conventional AC system.

Wow. I've thought about this, using tap water to cool the house, but it's so wasteful it was never more than a playful thought. But then the Netherlands' summers are reasonably survivable even if they make me feel shit all day and all night.

At the end of the day, net zero water is 'used' it is all returned to the ground.

Its actually a strong net water savings: the production of electricity in Montana uses around 16 gallons of water per kilowatt hour.

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.

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.

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

Yes, I don't get it either. The article implies that they reuse it for a while, and then dump. But I can imagine how filter and ion-exchange systems need water for back-flushing and other maintenance. So maybe there's some hard-to-avoid loss.

It's not being dumped, it evaporates.

Check https://www.google.com/about/datacenters/inside/locations/be... and https://www.google.com/about/datacenters/efficiency/internal... .

(Disclaimer: I work in (another) Google datacentre)

Evaporative cooling, like those cooling towers next to hydrothermal power plants.