Abstract: The system for prechilling the ambient water, derived from a pressurized source of ambient water, that is needed by an existing beverage dispenser machine and by an existing ice maker machine, includes a heat exchanger positioned outside of the dispenser machine. This heat exchanger receives the cold waste waters being discharged during use by both machines. A heat exchange tubing is immersed inside the heat exchanger for precooling, in heat exchange relationship, the needed ambient water with the cold waste water inside the heat exchanger. The prechilled ambient water is supplied to the ice machine for producing ice to fill the dispenser's bin, and the ice is supplied to the bin of the dispenser machine for cooling the dispenser's cold plate and for dispensing chilled beverages.