Reliable sanitation is an essential element of any thriving city, a required precursor to economic development and reduction of disease. The traditional approach has been to invest in sewer networks and wastewater treatment plants, even though they require huge commitment of capital to install, and significant ongoing investments - in highly trained staff to maintain and operate, replacement parts, electricity, and water - to keep them functioning.

Between now and 2030, the cities of sub-Saharan Africa and South Asia will see faster growth than any other region. Many of these cities are already experiencing water stresses, and as populations increase and climates change, these stresses will only grow. Such cities will simply not have the capacities to provide reliable sanitation via traditional water-borne systems.

To address this growing crisis, we need transformative innovation in our sanitation systems, from how services are organized, at the city level, to the new technologies that we will rely on. Catalyzing this system-wide innovation is the focus of the Bill & Melinda Gates Foundation's Water, Sanitation, and Hygiene program, and in this talk the program's director, Brian Arbogast, will share why solving the sanitation challenge is central to making developing cities healthy, livable, and more equal, and reveal the progress being made by the program's partners that gives him confidence that the necessary transformation is achievable.