[perching_aix]

Isn't the water used for evaporative cooling? Not much to return then I'd assume.

Edit:

Upon looking into it, looks like a portion of it (tens of percents) becomes a concentrated fluid called "blowdown", filled with minerals from the water source, and various treatment additives used for ensuring that the thing keeps flowing and doesn't become a growth media. This does need to be flushed out periodically, and is apparently supposed to be directed towards a water reclamation plant (e.g. via the sewage system).

I don't necessarily find it a reasonable suggestion that it should be cleaned in place, although it does look like a number of DCs actually do, but obviously I do agree it should not just be dumped yolo.