The decision of how to accomplish the renewal of existing wastewater collection and water distribution systems involves the evaluation of many criteria and parameters. These criteria must be evaluated thoroughly to determine the optimal approach for rehabilitating or replacing these systems efficiently and cost-effectively. The objective of this report is to: identify the current decision support methodologies, models and approaches being used for determining how to rehabilitate or replace underground utilities; identify the critical gaps of these current models through comparison with case history data collected from utilities; and assess the feasibility of substantially improving upon existing approaches. This report describes the current state of decision support models and methodologies used throughout the U.S. for determining how to decide whether to rehabilitate or replace existing wastewater collection or water distribution pipes. Eight case studies are provided to document how some of the major population centers throughout the U.S. make their decisions.