Why Tehran Is Running Out of Water

This communicative originally appeared connected Bulletin of the Atomic Scientists and is portion of the Climate Desk collaboration.

During the summertime of 2025, Iran experienced an exceptional vigor wave, with daytime temperatures crossed respective regions, including Tehran, approaching 50 degrees Celsius (122 degrees Fahrenheit) and forcing the impermanent closure of nationalist offices and banks. During this period, large reservoirs supplying the Tehran portion reached record-low levels, and h2o proviso systems came nether acute strain. By aboriginal November, the reservoir down Amir Kabir Dam, a main root of drinking h2o for Tehran, had dropped to astir 8 percent of its capacity. The contiguous situation reflects not lone this summer’s utmost vigor but besides respective consecutive years of reduced precipitation and ongoing drought conditions crossed Iran. As a result, the superior of Iran is present facing a imaginable “Day Zero” erstwhile taps could tally dry.

The drought rapidly disrupted Tehran’s municipality systems. With adust soils and precocious evaporation, rivers and wetlands shrank. Falling reservoir levels led to disruptions successful hydropower generation, and h2o shortages prompted strict redeeming measures crossed parts of the capital. Amid these escalating pressures, officials warned that the superior metropolis whitethorn adjacent person to beryllium evacuated if h2o supplies neglect to recover. In November, President Masoud Pezeshkian said the superior would person to beryllium moved. These cascading impacts exposed however susceptible Tehran’s infrastructure, economy, and communities person go nether compounding vigor and drought stress.

These cascading impacts stem from a prolonged shortage of precipitation successful caller years (Figure 1a). Precipitation astir Tehran typically peaks betwixt December and April, replenishing reservoirs down dams earlier the onset of the adust summer. Over the past 5 years, precipitation during this bedewed play has remained consistently beneath the semipermanent climatological baseline, with the 2024-25 play showing the astir pronounced and prolonged shortage crossed the full rainy season. When specified prolonged dryness was followed by an exceptionally blistery summer, it amplified hydrological accent crossed the region.