2 May

Map of the Week: Water in Istanbul

By Thomas Jang

The city of Istanbul, Türkiye, has served as the capitals of the Ottoman Empire and the Eastern Roman Empire as Constantinople. For centuries, the city has played an important role in connecting maritime trade routes around the Mediterranean and Black Seas, thereby connecting the continents of Asia and Europe. Its architecture has been influenced by major religions such as Orthodox Christianity and Islam, producing ornate churches and mosques, street plans, ancient defensive walls, and water supply systems. Today Istanbul is the largest city in Europe, with a population of 17 million people. 

Istanbul is situated across the Çatalca Peninsula, bordered by the Sea of Marmara to the south, the Bosporus Strait to the east, and the Black Sea to the north. These waterways significantly influenced the development of the city from ancient times. For centuries, from the early days of the united Roman Empire to Byzantium, the city was mainly confined behind the Theodosian Walls, which played an important role in protecting the city from Avars, Sassanid Persians, Russes, and Bulgars. Despite its location, the former Byzantine capital did not have access to sources of freshwater. Furthermore, the city had only a few natural springs, a situation exacerbated by long summers and low rainfall. 

In the Late Antiquity period (200 CE – 600 CE), a system of aqueducts were constructed. In fact, the city was already inhabited by half a million people. The system featured cisterns that stored water along the course of the aqueducts originating from water sources in Thrace. On the peninsula, there were several cisterns within the Theodosian Wall. These cisterns were either open and aboveground or closed and underground. Although it was not comparable to the aqueduct system of the western Romans, Constantinople’s water supply system was able to bring water from at least 75 miles (120 km) away along 310 miles (500 km) of channels. Many of the 200 cisterns from the Byzantine era around the city were built before the 7th century. 

Several prominent cisterns still exist and are accessible to this day. These include the Basilica Cistern, Theodosius Cistern, and the Cistern of Philoxenos. The former Cistern of Aetius was emptied by 1540, converted into a vegetable garden during the Ottoman Empire, and rebuilt in 1921 as a sports ground. 

Today, the ISKI (Istanbul Su ve Kanalizasyon Idaresi), a public utility, manages water supply and sanitation for the city. Features such as dams, water treatment plants and pipelines help transport water to the city through the European side’s Terkos-Alibeykoy system and the Asian side’s Omerli-Dalek system. However, many of the reservoirs part of these systems are polluted due to unplanned urbanization and little enforcement of conservation zones and buffer zones. The new Melen system is being developed to add more reservoirs, with the first phase completed in 2007 now supplying 268 million cubic meters of water. However, the second and third phases are projected to be completed in 2040, hoping to bring in 1,180 billion cubic meters of water. 

The provision of clean and reliable water has long posed a fundamental challenge to the human urban project. The waterways of Istanbul are a prime example of innovative responses to such a challenge. As humans enter into an age where more than half of the global populations live in cities, the storied history of Istanbul’s quest for water reminds us of the fundamental connection between urban areas, their residents, and the natural resources which sustain them. 


The Past – The city thirsts: Water in Istanbul: past, present, and future

The Byzantine Legacy – Aqueducts and the Water Supply System of Constantinople