Istanbul could run out of water within 45 days as Turkey continues to suffer from its worst drought in a decade.
Sprawling urban development has been blamed for dams drying up the city of 17 million people along with many of the country's other metropolises.
Water levels in the Omerli dam, the city's main water source, are at their lowest in the last 15 years - at just 20 per cent capacity due to a lack of rain.
Meanwhile in the capital Ankara, mayor Mansur Yavaş said there are only 110 days’ worth of water left in dams and reservoirs.
Turkey’s next two biggest cities İzmir and Bursa have seen their dams depleted to just 36 and 24 per cent respectively.
The situation is so dire that mosques were told to pray for rain in December under the directive of the Presidency of Religious Affairs.
But the country's water stores have continued to fall, with rainfall down by 49 per cent in November and below average since then.
Turkey produces just 1,346 cubic metres of water per capita per year, making it a 'water stressed' country.
It has faced a series of droughts since the 1980s due to urban sprawl, industrialisation, population growth and climate change.
Istanbul Technical University academic Sevinç Asilhan said Turkey has a semi-arid climate due to its geographical location and said the country's reduction in the number of forests and green areas has made the drought more severe.
She told Hurriyet Daily News: 'Natural environment, green areas and forests should be protected and afforestation should be done for sustainable water resources.'
Water management expert at the Istanbul Policy Center Dr Akgün İlhan told the Guardian: 'Instead of focusing on measures to keep water demand under control, Turkey insists on expanding its water supply through building more dams.
'Turkey has built hundreds of dams in the last two decades. The warning signs have been there for decades but not much has been done in practice.'
Dr Ümit Şahin said: 'In Istanbul, the most vital water basins, the last forests and agricultural land, [have been opened] to urban development projects: the new airport, the new Bosphorus bridge, its connection roads and highways.'
Ankara mayor Mansur Yavaş proposed a new Progressive Water Bill to the Metropolitan Municipality Council on Monday, which would introduced tariffs on water in order to limit use.
On January 5, he said: 'Our dam occupancy has decreased to 20 per cent and we have 110 days of water left.
'In order to prevent high consumption, there will be a gradual increase in invoices to use over 10 m³.'