Civica staff led the comprehensive development and implementation of multiple pilot inflow and infiltration reduction projects in the Region of York. The success of the projects has led to the creation of the Developer-Led I/I Reduction Program that is full supported by York Region. Civica managed the investigations, analysis, design, and implementation of I/I reduction measures. The work produced significant innovations related to rain and sanitary sewer data collection, developed new data analysis techniques, new field-testing methods, new sanitary flow models explicitly accounting for I/I reduction leading to more accurate sewer capacity assessment, and optimization of I/I reduction works for both peak flow and flow volume reduction. The work involved extensive flow monitoring (over 120 flow monitoring stations and 50 rain gauges), extensive data management and analysis. The program pioneered I/I source investigations using standard and new CCTV techniques (standard, wet, and dry CCTV video), smoke and dye testing, and maintenance hole inspections. Civica staff functioned as the project managers, program designers, and tool developers for rapid development and calibration of detailed integrated storm and sanitary drainage system models for I/I and sanitary and storm capacity assessment.