Utility partnerships with small-scale providers (SSPs) are becoming increasingly important as utilities struggle to serve a growing population and the poor in particular. This article explores a delegated management approach as one type of partnership, in which 'master opererators' purchase bulk supplies of water and are then responsible for collecting in water payments from their customers, and introduces the case study of this approach in Nyalenda, the largest slum of Kisumu, Kenya. The authors explore why such partnership innovations in service delivery are needed and what the impact has been on the Kisumu Water and Sewerage Company and on consumers. Here 'unaccounted-for' water has decreased dramatically as both the master operators as well as the utility share an interest in preventing illegal connections. The authors also provide recommendations for the scale-up of this approach in Kisumu and the replication of the delegated management model in other cities facing similar challenges to improve services to the poor.