The water isn't being used for its enthalpy of vaporization, so there's a huge difference between that and using water to transport heat in a closed loop. It's

The water isn't being used for its enthalpy of vaporization, so there's a huge difference between that and using water to transport heat in a closed loop. It's pedantic to worry about the amount of water in the closed loop since it is only lost due to shutdown maintenance activities or leaks. Since the goal is for things to work more than 99% of the time this does not constitute a huge consumption. If you are using glycol there is further incentive not to waste glycol additive which is required to be mixed in at a rate proportional to the refill volume.