In order to minimize the total regional cost for a Regional Wet Weather Management Plan (RWWMP), a cost-effectiveness analysis was proposed to optimize the amount of inflow and infiltration (I/I) reduction and capacity improvements needed. Individualized planning was performed for each of the nine wastewater treatment plant service areas that serve the Hampton Roads region in southeastern Virginia. This analysis was performed at a macro-economic level, recognizing that each treatment plant service area is unique in its existing infrastructure and current level of service. Finally, the study provides cost-effective curves representing how the associated I/I removal costs added to transport and treatment improvement costs determine the minimal total cost for each treatment plant service area. Lessons learned from this study could be applied to other utilities seeking cost-effective solutions for Sanitary Sewer Overflow (SSO) reductions and capacity improvements.