"Water consumption in the megacity surpassed 3.5 million cubic meters, of which 40% was from underground sources," Mohammadreza Ahmadnasab was quoted as saying by IRNA.

Groundwater accounts for 25% of the city's total consumption but when usage crosses the 3 mcm level underground resources are under added pressure.  

Although the heavy rains between February and April helped increase the water stored in dams, it did not raise water level in the rapidly drying underground tables, he added, noting that an estimated 250 mcm of water is extracted annually from underground sources for urban green spaces, according to Financial Tribune.

"Daily consumption in Tehran at 250 liters per capita is 20% higher than other cities in Iran and 30% above other megacities with the same population." 

Average daily consumption of Istanbul's 13 million population was 2 million cubic meters in 2007 and  increased to 3 mcm in 2016 when the population was reported at about 15 million. 

With a population of about 13 million people, Tehran has a 16% share in the country’s total population.

Water consumption in Tehran shot up by 4% in the past three months (March 21 to June 21) compared to the corresponding period last year, this is while annual population growth rate stands at 2%.

An estimated 278 million cubic meters of water was used in the sprawling capital between March 21 and June 21. The figure was 267 mcm last year.

Soaring temperatures over the last month (35°C and above) has made households and businesses crank up cooling systems that are very water-intensive. Majority of homes use the traditional evaporative coolers.

Referring to global standards, the senior water official  said average water use of a household of four is 15 cubic meters per month in the world. “In Tehran it is 30 cubic meters for almost 40% of households that account for 50% of the total water consumption in the city.

Potential Impact

Humans use over half of all accessible water runoff. They are the smallest consumers of water, but have a large potential impact. Users have the most influence at the household level and need to experiment with strategies to develop water saving habits. 

Household water use is the largest growing sector (upwards of 80% over the next 25 years). 

Estimates indicate that 40% of the world population lives in water scarce areas, and approximately ¼ of world’s GDP is exposed to this challenge. 

By 2025, about 1.8 billion people will be living in regions or countries with absolute water scarcity. Water security is a major – and often growing – challenge for many countries today.

Ahmadnasab believes wasteful water practices can be controlled if schoolchildren are taught about the importance of wise and sensible consumption from early ages. 

Experts describe lack of such basic training as the missing link between the education system in Iran and the Energy Ministry.

The official stressed that low prices for both farming and drinking is another contributing factor.

“Urban and rural consumers of potable water pay only 47% and 27% of the cost price of water respectively.”

Subsidizing agriculture, including water, he said, is a norm in many parts of the world, but paying closer attention to how and to what extent this makes economic sense has now become a fundamental question for policy and decision makers.