Residents of the Iranian capital, Tehran, have reported a scarcity of water, which last year prompted protests in several cities and last month led to clashes with neighbouring Afghanistan.
Video posted on Twitter showed long queues in streets where tankers distributed drinking water to residents.
Iran’s Minister of Energy Ali Akbar Mehrabian on Wednesday blamed the drop in supply to Tehran and the nearby city of Karaj on recent flooding that caused a landslide in the area surrounding the Karaj Dam.
“This incident happened downstream of the Karaj Dam and we had to open the 300-metre path,” he was quoted as saying by the state-affiliated Irna news agency.
"Therefore, they dug a channel in the minimum time and in 12 hours established the water connection between the dam and the downstream, and water started flowing towards Tehran and Karaj from Monday at noon."
Despite claims by officials that the water supply issue was fixed by Wednesday, footage published on social media overnight showed some users still struggling to obtain water from taps at home.
Karaj Dam, one of the largest in Iran, is a major source of water for the Alborz and Tehran provinces.
Drought, a problem in Iran for 30 years, has worsened in the past decade, the UN’s Food and Agriculture Organisation said. The Iran Meteorological Organisation estimates 97 per cent of the country faces with some level of drought.
Last summer, hundreds of protesters took to the streets in western Iran over a lack of drinking water and the inability of officials to solve the problem.
Iran has for years suffered chronic dry spells and heatwaves that are expected to worsen with climate change.
The Taliban and Iran exchanged heavy gunfire last month on the Iranian-Afghan border, killing and wounding troops as tension between the two countries, which are embroiled in a dispute over water rights, rose sharply.
Irna also quoted the country's deputy police chief, Gen Qassem Rezaei, accusing the Taliban of opening fire first on the border of Iran’s Sistan and Baluchestan provinces and the Afghan province of Nimroz.
The border clash came as Iranian President Ebrahim Raisi warned the Taliban not to breach Iran's rights to the waters of Helmand river.
Mr Raisi's remarks represented some of the strongest yet over long-running concerns over water supplies in Iran.
