The bank of screens in Ismail Aydin's Istanbul water management system control room flashes a worrying number: 29.7 percent.

That is the capacity level to which Istanbul's water reservoirs have dropped after another steamy summer put Turkey's largest city on the edge of a potential catastrophe.

Aydin does not want to sow panic and speaks in reassuring tones.

The rainy season is approaching and water levels should pick up in the coming weeks. But Aydin admits what the city's 16 million official -- and 20 million estimated -- inhabitants have known for some time.

"We've had a dry season," the water and sewage administration chief said. "Water levels were at 60 percent this time last year," he said. "It dropped down to 14 percent in 2014, so this is the second-lowest in the past 10 years."

Istanbul is surrounded by a web of 11 dams that fill up with water when the heaviest precipitation falls in November and December.  But global warming caused by human-caused greenhouse gas emissions is changing weather patterns and giving Aydin constant stress.

Istanbul has had barely any precipitation at all this summer and water usage has soared because of the heat. Turkey as a whole experienced the hottest July on record and broke the 50-degree Celsius (122-degrees Fahrenheit) mark for the first time in modern history on August 14.

Booming growth

The city could ship in extra supplies of water by sea or road should the dams run completely dry -- although no specific plans have been laid yet for that gloomy possibility.

Istanbul's problems are compounded by its phenomenal growth. The city had almost as many dams when its population was just over five million people 30 years ago and water consumption was not a hot topic in the news.

Officials now make regular media appearances pressing Istanbulites to conserve water any way they can.

 Aydin's department sent a mass text message during a particularly hot spell warning that the situation was becoming unsustainable. "The storage volume of our dams in Istanbul is approximately 868 million cubic metres. But Istanbul's annual consumption is 1.1 billion cubic metres," Aydin told AFP.

"Istanbul's (dams) do not have enough water to last a full year. Istanbul is a city in need of continuous rainfall. Our groundwater is not enough. "The lack of rain is turning some parts of the emptied dams into rolling meadows that flocks of sheep and goats roam on the city's outskirts.

Pensioner Nejat Karakas grew up around water and likes to visit the dams to while away the time.He leaned glumly against the side of an upturned rowboat lying on the cracked dry bed and contemplated climate change. "It makes me sad. We're not used to seeing it like this," the 68-year-old said. "If there is no rain between now and October, bad days await Istanbul."

Worried youth

Aydin's attempts to raise awareness and change Istanbulites' habits appear to be making some inroads. Driver Hasan Sadikoglu said he has fitted a large plastic bottle into his toilet tank to conserve a litre of water with every flush.

"When the children brush their teeth, the tap is opened and closed," the 53-year-old said. "One brush, one open." Aydin's department has also announced plans to install special devices on faucets of households that consume more than a set amount of water every month.

The idea is to reduce households' water pressure once the usage limit is breached. "Very effective measures should be taken, especially in water management," Aydin said. "Saving is a priority, recycling is a priority."

Student Mine Altintas said she already tries to conserve water while washing dishes and doing laundry. But she worries that this will not be enough. "All of us, the whole country and even the whole world, is worried," the 18-year-old said. "I don't know what will happen in 10 years. I am still young, and I don't know how much water we will have later on."