Public water supply intermittency and unequal urban water access: Insights from hydro-economic multi-agent modeling case studies in the Global South

Unequal water access will be a major driver of increasing water insecurity in the 21^st century, exacerbating the impacts of climate change. An estimated one billion people in cities in low- and middle-income countries currently face varying degrees of public water supply interruptions, subjecting them to unequal water access. This number is expected to grow, as water scarcity intensifies and supply infrastructure deteriorates. Yet, insights into the quantitative effect of water supply intermittency on urban water access inequality are so far limited. Here, we assess insights from hydro-economic multi-agent modeling case studies in South Asia and in the Middle East to analyze the effects of intermittent public water supply on the water security of heterogeneous urban household populations. We find that public water supply interruptions lead to severe disparities in household water consumption across cases. This also leads to household reliance on costly alternative water sources, jeopardizing water affordability. By 2050, climate change and population growth exacerbate the effects of water supply intermittency, causing severe deterioration in water security and increasing water access inequality. The results indicate that improved monitoring of water access inequality and reducing supply intermittency are key to mitigating urban water insecurity in the coming decades.