On the NYC, the pans used treated water from the nearby railroad water treatment plant. Those plants had boilers from old, previously retired NYC steam locomotives. The function of those boilers was to provide steam to bubble into the pan and keep ice from forming during winter operation.
NYCSHS has both drawings and articles published in the Central Headlight that describes this operation in detail. I can't recall the depth of the scoop into the water, but NYC engineers were advised to open the locomotive throttle completely when scooping water to minimize the drag of the water on the train,
If the scoop did not retract or retract completely, the scoop was sacrificed, as the pans had a clearance ramp that would damage the scoop and minimize damage to the pan. In 1945 (from my memory), Niagara #6002 running east from Chicago derailed with a number of cars in the train. A freight Mohawk had just passed over this track after taking water, and the scoop did not fully retract. The track was out of alignment since, after the Mohawk scooped water, it ran over a road crossing and tore up the crossing. (Some timbers from the crossing were found INSIDE the Mohawk's tender.) The dragging road crossing timbers knocked the track out of alignment.
Perhaps as a result of these types of problems, the ICC wanted the RR to install a warning system that would detect a dragging scoop.
This is a fascinating topic and shows how precious a few minutes on each run were to the railroad.