History of Water Management in İstanbul

Istanbul is a very significant settlement center in terms of geopolitics.  With the Bosphorus connecting Asia and Europe, and the Golden Horn named as “Haliç” in Turkish, as well as the surrounding seas, various cultures and civilizations that have existed here, İstanbul has enjoyed its position as a political, military and commercial center for centuries. 


The water need of the city during its foundation period was supplied through underground resources. The first significant water facilities in the city were constructed during the Roman Empire. Historic records show that Emperor Hadrian (117-138) commissioned the construction of a waterway from a distant resource to the areas by the Golden Horn, while Emperor Valens (364-378) did the same between Halkalı and Beyazıt, with the construction of the Mazur Aqueduct and the Valens Aqueduct commonly known today as Bozdoğan aqueduct. A dam was constructed during the reign Valens to collect water from Kağıthane stream through grids and pools and supply it to the city.

Theodosius I (378-395) brought water through a third waterway via Mazul and Valens aqueducts and constructed the fourth waterway between Belgrat Forests and the Sultanahmet area. The Roman and Eastern Byzantine emperors commissioned open (e.g. Çukurbostan) and covered cisterns too, with consideration of the drought and wartime possibilities. The most significant open cisterns are Aetius (Vefa stadium today), Aspar (Çukurbostan) and Hegius Mokius (Altınmermer) water storage cisterns. The most significant open ones today are The Basilica Cistern with 336 columns (Yerebatan), Pileksenus with 224 columns (Binbirdirek) and Acımusluk cistern.

Although the water structures constructed during the reign of Roman emperors were repaired to an extent at the time of the Byzantine empires, they were almost completely destroyed, impossible to use during the last decades of the Byzantine Empire. Among those structures, Mazul and Valens have been repaired by the Ottomans, thus surviving up until today.
Opening a new era with the conquest of İstanbul, the Turks have established a magnificent water civilization considering the conditions of those days. The city population increased further after the conquest and the existing water facilities proved insufficient. Mehmet II the Conqueror first restructured the water facilities that were constructed during the reign of Valens.
Later on various rulers and governors contributed to the Marmara region water facilities network fed by water from Halkalı area.

The daily yield of these plants was 4.335 m3, which was sufficient to feed the regions required. Mazul, Kara, Ali Paşa and Bozdoğan aqueducts were lined up along Halkalı waterways. Mazul and Valens aqueducts dating from Byzantine times were repaired to be reused. All these waterways enabled continuous supply of water to mosques, fountains, soup kitchens and army barracks in and out of the city center.

With the increase of population over time, water scarcity reappeared and Suleiman appointed Sinan the Architect to solve this problem. The construction of Kırkçeşme waterways thus commenced in 1555. In those days, water from Alibey and Kağıthane streams was collected and transferred to Eğrikapı through pools, then was supplied to the city. As there were no pressure-resistant pipes, aqueducts were built over valleys to maintain continuous flow paths.
The calculations conducted during their construction, at the identification of the main source, construction of pools and aqueducts were as accurate and precise as those made with today’s modern devices.

The system completed in 1563 includes the aqueducts of Uzun Kemer, Eğri Kemer, Güzelce Kemer and Mağlova Kemeri. Even during the driest seasons, Kırkçeşme waterways could feed 4.200 m3 of water into 158 facilities (94 fountains, 19 water wells, 15 troughs, 13 hamams, 7 palaces and 10 other structures). With additional structures commissioned by charitable people since the time of Suleiman, the number of units supplied increased. Reservoirs were built upstream to save water from winter to summer. These reservoirs located in Belgrat forest, also named as Kırkçeşme reservoirs were Karanlık Bent (Osman II, 1620), Büyük Bent (Ahmet III, 1723), Ayvad Bendi (Mustafa III, 1765) and Kirazlı Bent (Mahmut II, 1818). The yield of Kırkçeşme waterways rose up to 10,000 m3/day with these reservoirs.

The first water issue around Beyoğlu area in İstanbul was resolved with the construction of Taksim water facilities in 1732. Water collected from around Bahçeköy with a daily yield of 800 m3, is supplied to a tank of 2.700 m3 volume in Taksim through a line of 20 km and then to 64 fountains and 3 water tanks. Bahçeköy aqueduct was constructed in 1732 by Mahmut I and Topuzlu Bent reservoir as well as Valide Benti and Mahmud II Bent. The daily yield of Taksim waterways increased to 3.000 m3.   

In order to meet public demand, the spring waters were provided through small transmission lines on public fountains. The most significant example of this is Hamidiye water constructed by Abdulhamid II in 1904 with a daily yield of 1.200 m3. This system provided water from Kemerburgaz springs to army barracks, palaces and 50 public fountains around Beyoğlu. Kanlıkavak and Sarıyer waters transmitted to Emirgan are also such spring waters. Those on the Asian side are Kayışdağı, Atikvalide, Küçükçamlıca Alemdağ (Taşdelen) waters as well as Ten Fountains, Karakulak and İshakağa waters in Beykoz.

To meet the water demand of the city with its growing population that needs more water, as well as to provide pressure water to new modern buildings, “Dersaadet Anonim Su Şirketi” (Water Inc.) was chartered to a French company in 1868 by Abdulaziz. This company had the duty to supply water to the city from Terkos Lake and collect other spring, underground and stream waters to transfer upon treatment.

The first facility constructed was the pumping station located next to Terkos Lake in 1883. The connection structure that would raise the level of lake side was completed in 1888. In 1926 the first water treatment unit was constructed on the hills of Kağıthane and the water was treated to be distributed to the city from here upon chlorination. On the other side, to meet the water demand on the Anatolian side, 1st Elmalı dam was constructed on Elmalı stream in 1893 by Üsküdar-Kadıköy Water Company while a new water network was laid between Anadoluhisarı and Bostancı. Later a pumping station and treatment plant for Elmalı dam as well as a storage tank at Bağlarbaşı were constructed by the same company.

In time these companies with privileges were seen to avoid their duties while enjoying many rights and the common opinion was that water issues could not be resolved by these companies. In 1932 Terkos company and in 1937 Kadıköy-Üsküdar water company were purchased and transferred to İstanbul Water Administration (İSİ). Those days the total amount of water provided was around 35.000 m3/day. With the continuous work of İSİ on European side, the capacities of Terkos Pumping Station and Kağıthane Treatment Plant increased as second transmission lines were reinforced and electric pumps replaced steam pumps. Artesian wells were opened in Çırpıcı and a pumping station was constructed on the site.

A power transfer line was laid between Terkos and Silahtarağa and the pumping stations in the former location were filled with electric pumps. Transmission lines and water distribution networks on Ömerli dam constructed by DSİ (State Hydraulic Works) were completed. A second dam on Elmalı stream was constructed and electric engine pumps were installed at the pumping station here. The treatment plant was rehabilitated. Pumping stations and water scaffolds were installed on the Prince Islands. Transmission lines and water distribution systems at Ömerli constructed by DSİ were completed.

However, over time, the infrastructure in İstanbul failed to improve and ghetto neighbourhoods made distribution of services harder. The need for a new administration with broader authority and abilities was seen as İSİ failed to meet the increasing population’s water and sewerage demands.

The name of the new administration founded in 1981 is İstanbul Water and Sewerage Administration (İSKİ).

İSKİ was founded under the governance of İstanbul Governorate with the Law no. 2560 and serves under the Metropolitan Municipality of İstanbul in 1984 under the Law no. 3009. The Metropolitan Municipality Law no. 5216 issued in 2005 extended the service area of İSKİ and increased the districts served from 27 to 39. As certain water resources to supply İstanbul were outside the municipal borders, the duty area of İSKİ was extended with a Ministerial Board decision to include Istranca stream basins as well.