In order to comply with emerging Sanitary Sewer Overflow regulations expected from US EPA at the end of Year 2000, many municipal agencies want to know the most effective ways to remove infiltration and inflow (I/I) within their systems. The question for these agencies is, “How much do I need to remove, and where’s the best place to do it?” For many communities, the decisions on what sort of I/I removal to undertake can be a daunting task. What is most concerning these communities is what can they learn from other communities that have already gone down the I/I removal path. Brown and Caldwell in association with the University of Washington (UW) is performing a project for the Water Environment Research Foundation to identify and develop Predictive Methodologies for Determining Peak Flows after Sanitary Sewer Rehabilitation (Project 99-WWF-8). Methods that allow municipal agencies to estimate peak flow reductions resulting from specific I/I reduction activities will benefit agencies seeking to reduce the amount of infiltration and inflow (I/I) reaching the sewer system. Several realities have come to light while performing the survey work thus far on this project. Most of the I/I removal projects in the country go undocumented. Second, what few I/I removal project summaries that have been published have provide very little hard data. Data gathering and analyses have been hampered by lack of documentation, lost or unavailable monitoring data, and weaknesses in monitoring techniques. As the project team must base any predictive methodologies only on projects with solid documentation, the WEF conference provides an important venue to encourage communities to be more diligent in gathering the right data and report comprehensive results in technical journals. This paper presents the objectives for this important WERF project, supplies the approach to performing the work, and provides an update on progress to date. The paper is intended to raise the awareness of a general lack in reporting I/I reduction projects and how many of the reported projects lack important documentation.