Within the chemical and allied process industries, the power production unit is one of the main facilities that use large volumes of water and steam as the prime utilities. These utilities are generated in boilers and cooling tower systems, respectively. Thus, it follows that any optimisation effort aimed at improving the operation and profitability of a power plant should at least focus on these utility systems. Indeed, optimisation methods for the two systems are available in the published literature. However, most of these published methods have ignored the complementing and synergistic aspect of the two utility systems as found in real power plants - and have treated their optimisation in a separate and discrete manner. Such individual analysis creates a false dichotomy between the boiler and cooling water systems and generally gives suboptimal results. The two systems constitute a comprehensive utility system and should be optimised in a single approach.