Many water operators in developing countries have serious knowledge and capacity-related challenges that lead to poor service delivery. Water Operator Partnerships (WOPs) are used to strengthen the capacity of water operators for improved performance, by transferring knowledge from mentoring water operators to mentee water operators. Knowledge management (KM) within water operators requires urgent attention to ensure that the knowledge that is acquired in the context of WOPs is applied to help improve performance. The objective of this study is to investigate the KM processes of water operators and the factors influencing these processes. This study uses a qualitative case study approach, comparing three water operators involved in WOPs: two in Sub-Saharan Africa and one in South America. We use the Knowledge Value Chain by Weggeman (1997) to analyse the KM processes of these water operators. Data was collected using a variety of instruments, notably, via interviews, focus group discussions (FGDs), non-participant observation and desk research. We analysed the individual cases first, followed by a cross-case analysis. A large scale survey among US water supply operators showed that more than 50% of the operators are already implementing KM strategies. However, little is known about the extent to which and how water operators in developing countries implement KM; yet arguably they are most in need of sound KM practices to improve their service delivery. The insights into KM processes of “WOPping” utilities and the factors influencing these processes enable us to identify the most salient KM-related challenges faced by water operators and provide the basis for a structured approach to address these challenges. The analysis shows that in their efforts to implement KM, these water operators put emphasis only on selected KM processes. Organisational factors (e.g., structure, management style) appear to influence KM processes to a great extent. Moreover, the implementation of KM sometimes seems to be done in a haphazard way, partly due to a lack of clearly articulated knowledge vision and strategy. The successful implementation of KM by water operators appears to require (1) a multi-dimensional approach; i.e., focusing simultaneously on individual and organisational aspects of KM, (2) the use of both technological and non-technological approaches, and (3) a KM coordinating mechanism at organisational level. Most fundamentally, water operators need to appreciate the added value of KM and support it.