- water
- cooling
- data-center
Once-through cooling draws water, runs it once through a heat exchanger, and returns almost all of it to the source. Its signature is a large withdrawal but a small consumption: the water comes back, chiefly warmer. The environmental question it raises is thermal — the heat load and intake entrainment — rather than lost flow.
It is the mirror image of closed-loop cooling, and the distinction is decisive for the water balance. A once-through data center barely dents downstream flow but adds a thermal load a receiving water may not tolerate at low flow; a recirculating one withdraws far less yet consumes most of what it takes through evaporation. Which design an operator chooses therefore determines whether a campus reads as a consumptive cooling problem or a thermal one — so the platform keeps the cooling type an explicit, sourced assumption, not a guess.