Istanbul's early water supplies began under the reign of the Roman emperor, Hadrianus, but in time the volume of water from the rivers close by became inadequate. The Istranca mountain range, many kilometres along the Black Sea coast, northwest of the city, then became the basis of the water supply system for many centuries.

In the 4th Century, the Roman emperor, Valens, instigated a project to carry water from its source in the mountains to the city via several aqueducts, pipelines and inverted siphons.

The aqueduct still visible in Istanbul's main street is named after its benefactor, Valens.
Reliance on the aqueduct to convey water disappeared many years ago, and regrettably, massive sections have been destroyed by the city's development and extension.

Water travelling along these conduits not only supplied fountains, it travelled by pipelines into what were commonly called cisterns, for reticulation throughout the city. The fountains were not decorative, they were the community's water source. Women visited the fountains every day, carrying earthenware jugs of water back to their homes.
By the 7th Century, it is said the closed and open cisterns had a storage capacity of about a million cubic metres.

YEREBATAN CISTERN

The Yerebatan Cistern is probably the most famous. It is also called the Great Basilica Cistern because it is thought there was a great bascilica near it in the 3rd and 4th centuries, where trade, legal, scientific and artistic activities took place.

Built between 527 and 567AD, the locals also call it Yerebatan Palace, due to the numerous columns - about 376 - which rise out of the water to support the roof.
Measuring some 140 x 70m, and about 10m high, this amazing structure is a must see for anyone interested in water supply and engineering.

The cistern is underground. Access is through ancient housing at street level and down numerous steps. Once on the floor of the cistern, one can see various styles of columns. Two are supported by bases carved with Medusa's head. There are many theories and stories about why they are part of the construction, but no one knows for sure the origin of the bases, the reason they are there, or why one is upside down and the other is on its side.

Medusa's head

The cistern is contained in a combination of stone walls, marble and granite columns, and a roof of brick arches in intricate patterns.
Some of the column faces have been spoilt by repair work in the 1950s, when concrete reinforcement was applied to prevent further deterioration.

During a visit to the cistern, you can sit drink coffee and admire the surrounds in an area at the base where musical and other cultural events are occasionally performed. Additionally you can see the "Tear Column" said to have been constructed as a memorial to the hundreds of slaves who died during the construction period.

The Tear Column

ISLAMIC INFLUENCES

In the middle of the 15th Century, Turkey was invaded by Islamic forces, which led to the introduction of the Ottoman Empire.
According to Islamic doctrine, still water is not clean or suitable for human consumption. Only water flowing constantly from streams and rivers is acceptable. For a short period after the Ottoman conquest of Istanbul, water from the cisterns was used to water the sultan's palace gardens and some of the decorative fountains. Potable water had to be obtained from another source.

Mehmet the Conqueror and his grandson Suleyman the Magnificent increased the existing water supply by building new dams and aqueducts to supply the fountains throughout Istanbul.
The cisterns ceased to serve any useful purpose and lay unused and largely forgotten for some centuries. When the Yerebatan Cistern was rediscovered, its value was recognised by historians and others. Steps where taken to clean out and restore the cistern - 50,000 tonnes of mud and debris were removed and a walking platform was built for tourists.

The cistern is much more than an interesting tourist destination. It represents the basis of an early city's water supply and reflects the engineering principles and skills of the day.

Those principals are as valid and amazing today as they were when construction started around the 4th century AD.
The fascination with these constructions is tempered only by the difficulty in establishing a correct sequence of events.

The skill of the designers leaves the modern observer with a sense of wonder and admiration.
One last point about Turkey's water supply - don't drink it! The water will invariably bring frequent visits to the Asian style toilets.
But that's another story!

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Written by Cliff Hensby