This working paper describes water access challenges in cities of the global south that have been hitherto largely invisible in global indicators. In analyzing 15 cities, we found that piped utility water is the most affordable option, yet, on average, almost half of all households lack access, and most of those that do have access receive intermittent service. This paper highlights four key action areas for cities to improve water access: extending the formal piped water network, addressing context-specific causes of intermittent water service, pursuing diverse strategies to make water affordable, and supporting informal settlement upgrading.