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Toronto uses the [Deep Lake Water Cooling System](https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System) to extract "cold" from lake water before it is treated and used for drinking water.

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Sucks for the “free” cooling we get from cool tap water.

Takes a little load off the water heater I do have to admit. Unless you have a heat-pump based system, which is the trend…

It has nothing to do with tap water, they provided false information. It is pulling cold water from the lake, running it through heat exchangers throughout the system, then the cold liquid at each system is used to cool the buildings, etc. The slightly warmer water goes back into the lake, not into the drinking water system.

Incorrect. The heat exchangers are a part of the city water intake.

Edit: looks like a bit of both? See pg. 6:

https://www.toronto.ca/wp-content/uploads/2020/05/963d-ppfa-...

Though the city drinking water is pulled from deeper out so probably that supply is cooler to begin with:

https://www.toronto.ca/wp-content/uploads/2020/05/963d-ppfa-...

It is not used for drinking water, and the link you shared also doesn't mention that, but it is an interesting system that should be used in more places.

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