In Istanbul, where daily consumption is around 3 million cubic metres, water reservoir levels have continued to fall despite a marked increase in rainfall, mainly due to consumption in this mega-city of 16 million people. The situation has reached a point where the Ömerli dam, one of the city’s main sources of drinking water, is below 15%: the receding water has left large areas completely dry, as shown by aerial images revealing the extent of the drought.
According to data from the Istanbul Water and Sewage Administration (İSKİ), the water reservoirs supplying Istanbul received 93.49 millimetres of rainfall in October 2025, the third highest figure in the last decade after records in 2015 and 2020. However, despite this above-average rainfall, reservoir levels have continued to drop significantly over the same period, threatening the city’s drinking water supply.
As of 1 December 2025, according to Turkish media reports, the total occupancy of Istanbul’s dams averaged 18.27%. In the case of the Ömerli dam, however, the level is only 14.88%; but the most critical images are those that can be seen in the Kazandere and Pabuçdere reservoirs, where the water level has fallen to 2-3%, leaving them practically depleted. Experts warn that these values pose a severe risk to supply if sufficient rainfall does not arrive in the coming months.
Saving water, key to securing Istanbul’s supply
Professor Hüseyin Toros, a well-known climate scientist at Istanbul Technical University (İTÜ), confirmed to the media that October’s rains were higher than usual across the country and helped slow the rate of decline.
However, Toros stresses that Istanbul’s growing water demand and climate variability keep the situation at a critical point, which is why he insisted on the urgent need to reinforce water saving measures, both through sustainable management and individual behavioural changes, which he said are essential to guarantee the city’s water supply.
Data from the İSKİ show the following situation in Istanbul’s main water reservoirs as of 1 December 2025:
- Ömerli: 14,88%
- Darlık: 28,02%
- Elmalı: 49,79%
- Terkos: 20,47%
- Alibey: 11,04%
- Büyükçekmece: 19,88%
- Sazlıdere: 17-18%
- Kazandere: 2-3%
- Pabuçdere: 2-3%
Aerial images taken with a drone confirm the sharp decline of water reserves in key reservoirs such as Ömerli, Alibey, Kazandere or Pabuçdere, reviving concerns about Istanbul’s water security. Experts warn: if rains do not improve the drought situation in the coming weeks, restrictions and water cuts could be implemented.
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Edited and reviewed by:
Pablo Gómez is a specialist in Turkey and has been editor-in-chief of Hispanatolia since 2011. He has been analysing current affairs and geopolitics in Turkey and the surrounding region since 2006.
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