The water passes through a stainless-steel coil that is, itself, in contact with a copper evaporator coil, which contains the refrigerant gas responsible for ultimately chilling the water.
Direct chill is a simple, practical and highly effective way to chill water rapidly.
Its principal advantage over other cooling systems is that the water flows continuously through the system, rather than sitting waiting to be dispensed, and so bacterial proliferation - a constant bugbear of other cooling systems - is no longer an issue.

The water supplied from the mains or from the bottle is conducted into the reservoir, where, thanks to the lower temperatures, it rapidly becomes chilled.