This Blue Book of the International Network of Water and Sanitation Utilities (IBNET) is designed to raise awareness of how benchmarking and specifically IBNET tools can help enhance utility performance and thereby help to improve urban water and wastewater services. As the largest public water sector performance database IBNET provides comparative information on utilities’ cost and performance indicators. IBNET set and implemented the first global benchmarking standard for the water and wastewater sector. Since its establishment in 1996, the IBNET program has grown into the largest publicly available water sector performance mechanism that collects, analyses and provides access to the information of more than 2,500 water and wastewater services providers from 110 countries around the world. IBNET serves the interests of many. Utilities can use IBNET tools to identify areas of improvement and set realistic targets; governments can use it to monitor and adjust sector policies and programs, while regulators can use it to ensure that adequate incentives are provided to improve utility performance while consumers get value for money; consumers and civil society can use it to exercise, where necessary, valid concerns about service provision; international agencies and advisers can evaluate the performance of utilities for lending and client advice; and private investors can identify opportunities and viable markets for investments.