Learning from intermittent water supply schedules: Visualizing equality, equity, and hydraulic capacity in Bengaluru and Delhi, India

Intermittent distribution affects one in five piped water users, threatens water quality, and magnifies inequity. Research and regulations to improve intermittent systems are hindered by system complexity and missing data. We created four new methods to visually harness insights from intermittent supply schedules and demonstrate these methods in two of the world's most complicated intermittent systems. First, we created a new way to visualize the varieties of supply continuities (hours/week of supply) and supply frequencies (days between supplies) within complicated intermittent systems. We demonstrated using Delhi and Bengaluru, where 3278 water schedules vary from continuous to only 30 minutes/week. Second, we quantified equality based on how uniformly supply continuity and frequency were divided between neighbourhoods and cities. Delhi provides 45 % more supply continuity than Bengaluru, but with similar inequality. Bengaluru's infrequent schedules require consumers to store four times more water (for four times longer) than in Delhi, but Bengaluru's storage burden is more equally shared. Third, we considered supply inequitable where affluent neighbourhoods (using census data) received better service. Neighbourhood wealth was inequitably correlated with the percent of households with piped connections. In Bengaluru, supply continuity and required storage were also inequitably divided. Finally, we inferred hydraulic capacity from the coincidence of supply schedules. Delhi's highly coincident schedules result in city-wide peak flows 3.8 times their average – sufficient for continuous supply. Bengaluru's inconvenient nocturnal schedules may indicate upstream hydraulic limitations. Towards improved equity and quality, we provided four new methods to harness key insights from intermittent water supply schedules. [Display omitted] •We present new methods to visually learn from intermittent water supply schedules.•Infrequent, irregular, inconvenient supplies increase consumer storage and water age.•Average-based indicators obscure inequalities and inequities in intermittent systems.•Delhi and Bengaluru inequitably have 3278 schedules ranging 24 × 7 to 30 min/week.•Coincidence of supply schedules suggests hydraulic feasibility of continuous supply.