Brett Hetherington writes:

> It'll work as long as the OP doesn't expect to put too much volume
> through it.

"Too much", unfortunately, is less than even a single serving.

> A 5 gallon bucket of refrigerated water represents a heat sink
> to be reckoned with, given enough surface area.

No, because it's temperature rises, as does the output, as it is used.

You need a phase-change source to have controlled output temperatures.
Every commercial beverage chiller works on this principle.

Thermal-mass chilling is inefficient and costly per unit of delivery.