The 2020 Sustainability Index (SI), a benchmark system, shows that 2% of the 184 municipal water and wastewater utilities (WWS) in Sweden have a good performance level (green), i.e., they meet all benchmark requirements for the "climate adaptation and flood safety" ("CA and FS"). In this study, ten Swedish WWS organizations were selected and studied in depth. The goal was to present them as good learning examples to inspire other utilities seeking to improve their results and to clarify and concretize the driving factors, strategies, and important explanations for their success, and the challenges they face. A total of 52 SI annual documents from ten utilities were analyzed. Six of their managers were interviewed in depth. One of the ten utilities studied was green on the parameter "CA and FS". Flooding events in two utilities drove climate adaptation. The formation of an interdisciplinary group in two organizations had a major impact on their success. Two utilities focused on low-lying sites and enclosed spaces. Three believed capacity building increased their chances of success. The biggest challenge was sharing responsibility. That only 2% of municipal water and wastewater utilities are green is not the whole truth. Therefore, there should be other factors in SI that measure performance in "CA and FS". To improve the results, new laws are needed to solve the problem of shared responsibility.