Good point. the process of ebulition of disolved gases draws up energy and freezes the water.
If his pump is cavitating and then compressing gases , then when you open the tap the gasses bubble up which draws up energy and cools the water perhaps
Thank God I’m a country boy ...
“If his pump is cavitating and then compressing gases , then when you open the tap the gasses bubble up which draws up energy and cools the water perhaps”
Net-net, the pump heats up the water.