Estimating groundwater budgets in developing countries is especially difficult because of the variety of water sources residents use and the inconsistency of supply.

In India, no city receives 24-hour water supply, so residents draw their water from a variety of sources, including utility piped supply, tankers, private groundwater wells, bottled water and untreated water bodies. As a result, authorities do not know the true volume of water consumed by their inhabitants.

In order to address these gaps in information, we began monitoring groundwater levels in 154 wells across Bengaluru monthly, with the aim of understanding the groundwater budget and the influences of space and time, aided by data and models. From those measurements, we were able to estimate the city’s daily water use and determine that it experienced a net negative groundwater balance.