In urban slumshome to approximately 1 billion people worldwide-access to clean drinking water is woefully inadequate despite the United Nations' declaration that access to safe water is a fundamental human right. Households in slums are frequently forced to rely on multiple drinking water sources to meet their needs. Numerous factors influence choice of water source, including water quality, availability, reliability, and affordability. These factors are not temporally static, but rather will vary over multiple timescales (from sub-daily changes to annual changes and beyond) in response to changes in the water source itself and changes in the household's ability to use that source. For example, the cost of water can change over time in response to water availability (e.g. rainy season versus dry season) and a slum household's ability to pay for water will often change over time in response to changes in household income. However, existing national and global monitoring of safe water access, including Sustainable Development Goal 6, overlook these temporal dynamics of water access, quality and health risk in slums. This paper proposes a research agenda for exploring temporal changes in drinking water access and quality in urban slums and their potential influence on health risk. It argues that in the design of research studies, policy interventions, and drinking water monitoring aimed at improving access and health in urban slums, temporal dynamics 2 should be considered over at least three interlinked time scales: short-term (from sub-daily to week-to-week), medium-term (from month-to-month to season-toseason) and long-term (from year-to-year). The paper concludes with recommendations for future research on temporal dynamics of drinking water and health in slums.