After torrential rains in Tehran last week, potable water in Karaj and Latyan Dams became terribly muddy and water treatment plants stopped working for 14 hours, managing director of Tehran Province Water and Wastewater Company said.
“Reduction in water pressure and quality in homes in Tehran (especially in the east and southeast) on Friday and Saturday was due to above-normal mud levels in dams that created problems in the network,” Mohammadreza Bakhtiari was quoted as saying by ILNA.
In muddy conditions (when mud concentrations are above 10,000 units in rivers and dams) treatment facilities stop working because the maximum mud concentration they can process is 4,000 units.
He noted that the problem was solved and water in the network is now at normal pressure and quality.
Groundwater and dams account for 70% of water supply in the province and the balance (30%) comes from underground resources.
Referring to the unexpected rise in water consumption over the last ten days (after the outbreak of coronavirus and persistent washing of hands), he warned that water use has risen by at least 5% and if it keeps rising, (water) paucity in the province will become a real problem.
“As consumption rises water tables will come under mounting pressure and as a result quality will suffer.”
Average daily water consumption in Tehran has exceeded 3.3 million cubic meters, which is unusually high at this time of the year.
“To help conserve water resources from pollution (coronavirus), all treatment plants have been ordered to keep chloride concentrations above 8 ppm (parts per million).”
Tehran accounts for less than 1.1% of the country’s land area, but accounts for 20% of the population and 45% of the industrial base. This means high and rising water consumption.
Differing Quality
In related news, Seyed Hassan Razavi, managing director of Tehran Regional Water Company, noted that the quality of tap water in Tehran differs from one district to another.
Unlike the southern end of the city, tap water in uptown Tehran is not mixed with underground water and comes (mostly) from surface waters (dams) and has better quality, he said.
Referring to nitrate contamination, he concurred that wells are more vulnerable than dams. Nitrate contamination can occur particularly in shallow wells, wells with casings that are not watertight and wells with damaged leaking casing or fittings. Too much nitrate in potable water is a risk to infants less than six months old.
Tehran water quality was better in the past due to greater use of surface water and dams than well water.
However, regardless of the quality it is safe.
Tehran dams, namely Taleqan, Latyan, Mamlou, Karaj and Lar together can hold 1.93 billion cubic meters of water.
Dams across Iran can hold a maximum of 50 billion cubic meters of water.
According to the last report by the Iran Water Resource Management Company, there are 193 dams, of which 37 are 90% full. There are 37 dams in which the amount of stored water is less than 40%.
Around 30 bcm of water is now stored in dams.
