In this study EPANET, a widely used water distribution package was linked to OptiGa, a Visual Basic ActiveX control for implementation of genetic algorithm, through Visual Basic programming technique, to modify the computer software called OptiNetwork. OptiNetwork was applied to Badarawa / Malali distributionnetwork consisting of 96 pipes of different materials, 75junctions, two tanks, and a source reservoir (i.e treatment plant) from which water is pumped through a pumping main to the overhead reservoir and later distributed to the network by gravity. After several runs the cost obtained from this network using OptiNetwork software under the application of genetics algorithm is $433,520.00which is lower than $435,118.00 obtained from OptiDesigner software. This difference is approximately 3% lower than the result obtained from OptiDesigner (a commercial software) with minimum pressure head of 3m and maximum of 100, Pressure penalty of 200,000 and probability of mutation equal to 0.03, also the commercial diameters of 4”, 6”, 8”, 10”, 12”, 14”, 16” 18” 20’’, 22’’and 24’’ dmin =4”, dmax = 24” were used for the distribution network during the optimization process. The results obtained shows that the introduction of the modified software (OptiNetwork) is justified. This is because it has been able to improve the search method in terms of achieving the “least-cost” designed water distribution system that will supply sufficient water quantities at adequate pressure to the consumers.