EghtesadOnline: Potable water consumption in Tehran has surpassed 500 million cubic meters since the beginning of the current fiscal year (March 2021-22) while precipitation has declined by at least 40% in the period compared to 2019, the head of Tehran Water and Wastewater Company said.
"The figure indicates that water consumption in the sprawling capital over the period has been at least 3.5 mcm/d that is unprecedented in the history of the metropolis," ISNA also quoted Mohammad Reza Bakhtiari as saying.
“Water consumption in summer had never reached 3 mcm/d in Tehran before 2019. However, soaring temperatures, the Covid-19 outbreak and the need to adopt health safety measures have made a bad situation worse.”
In normal conditions, average water consumption in Tehran is 2.5 times over the global average.
Average water consumption in most cities and towns has declined from 250 liters per day to 150 liters, whereas the figure hovers around 300 liters for at least 40% of households in Tehran.
“Tehran Province accounts for 25% of total water consumption in Iran, which is around 100 billion cubic meters,” he said.
“Close to 170,000 heavy consumers [those who consume more than 30,000 liters per month] have been notified by TWWC and their supply will be cut off unless they curb consumption.”
According to the TPWWC boss, annual consumption growth in Tehran was 4% between 2010 and 2018 in line with population growth, which reached 11% in 2019 and 2020.
Bakhtiari noted that an increase in temperature by 1 degree Celsius raises water demand by 70 million liters.
“The weatherman has forecast a rise in temperatures over the next few days in the capital because of which water demand is predicted to exceed 3.7 mcm per day. Nonetheless, there are no plans to ration water anywhere in the province,” he said.
“Dwindling snow reserves in East Tehran are causing renewed concern; when snow reserves decline, inflow of water into dams also falls. At this time of the year, we have always had 6 to 6.5 meters of snow on the mountains around the Latyan and Lar dams in east Tehran. But now the maximum height is an alarming one meter.”
Surface water, including runoffs, is limited and when snow reserves fall, water inflow into the dams decline, creating in its wake new challenges.
The five dams include Latyan, Lar, Mamlou, Taleqan and Amir Kabir. Together, they held 1.8 billion cubic meters of water last year; however, the level now is 700 mcm.
Referring to water supply capacity in Tehran, Bakhtiari noted that close to 3.8 mcm of water can be transferred from dams around the city (namely Taleqan, Latyan, Mamlou, Karaj and Lar) to water treatment facilities on a daily basis.
“If necessary, all water treatment plants will operate at full capacity, in which case the volume of treated water can reach 4 mcm/d,” he added.
Bakhtiari reiterated that pathogens (coronavirus or any other virus) cannot contaminate the water supply and distribution chain as chlorine levels (at least 4 milligrams per liter) are high enough to destroy the viruses.
“Covid-19 virus has not been and will never be detected in drinking water”, as current drinking water disinfection practices provide the means to control most pathogenic bacteria and viruses responsible for major waterborne diseases, he said.
Bakhtiari said chlorination has been the predominant method of drinking water disinfection all over the world for nearly 70 years.
Chlorine, a strong oxidizing and disinfecting agent, is used not only as the main disinfectant in water treatment, but is also added as a residual disinfectant to preserve the water’s quality in the distribution process where chlorine is in contact with water for much longer periods during treatment.