This series contains data on water quality, sanitary risks and patterns of water use by owners and customers of different groundwater sources in Kisumu, Kenya. Sanitary risk inspections were made and water samples taken from wells in the Manyatta and Migosi, and in some cases Nyalenda and Bandani, areas of Kisumu during February and March 2014. During the same period, well owners and customers were surveyed to find out about use patterns of the ground water abstracted. The survey also included questions about access to assets and services (e.g. electricity, toilet facilities) and questions to assess food poverty. Water samples were analysed in a laboratory for microbiological indicator bacteria (thermotolerant coliforms) and chemical contaminants. The data were collected as part of the Groundwater2030 project, which aims to reduce the health problems that result from consumption of contaminated groundwater in urban areas of Africa. The project was co-ordinated by the University of Southampton, with partners at the University of Surrey, the Victoria Institute of Research on Environment and Development (VIRED) International, and the Jaramogi Oginga Odinga University of Science and Technology. The project was funded by the Natural Environment Research Council and the Department for International Development as part of the Unlocking the Potential of Groundwater for the Poor (UPGro) programme.