Abstract: An uninterrupted sub-loop water cooling system for supplying cooling water to a process machine during a short-term power interruption and a method for utilizing such system are disclosed. In the system, a buffer tank is provided for storing a quantity of cooling water maintained at a temperature of about 15° C. The buffer tank is provided with conduits for fluid communication with a process machine and at least one pump means operable by an uninterrupted power system such as a battery back-up system for pumping cooling water from the buffer tank to the process machine and then return to the buffer tank forming a sub-loop when a power shortage has occurred. The present invention system is effective in bridging a time gap between the occurrence of a power outage and the start of an emergency power generating system which amounts to between about 30 seconds and about 2 minutes such that cooling water supply to a process machine is not interrupted.