Fair. You are probably correct about dumping into waterways. But I know that a substantial amount of warm water is dumped into local wastewater processing.

My understanding is that a data center can be open loop or closed loop. Closed loop is like a water cooling pc with a radiator and you have to cool the water down to ambient temps. Open loop (or semi open loop) is more common which involves dumping hot water into the local sewer system or local waterways.

More data centers than you expect just dump the water rather than cool it down and reuse it.