The head of the United Nations agency UNICEF condemned on Tuesday an air strike on a water treatment plant in the Syrian Province of Aleppo on Thursday that cut the water supplies of 3.5 million people.
Although the pumping of water was partly fixed, about 1.4 million people still have a reduced supply.
UNICEF said that the air strike was an attack on civilian infrastructure and that it broke the rules of war.
"In Syria, the rules of war, including those meant to protect vital civilian infrastructure, continue to be broken on a daily basis," UNICEF's representative in Syria Hanaa Singer said in a statement.
"The air-strike which reportedly hit al-Khafseh water treatment plant in the northern city of Aleppo last Thursday is a particularly alarming example," she added.
On Monday, eight people were killed, 18 others wounded in Russian air strikes on humanitarian aid trucks in northern Syrian province of Aleppo.
The incident comes a day after Russian jets bombed a bakery built by a Turkish humanitarian aid foundation in the city of Idlib, northwestern Syria.
Russian has conducted an aerial campaign in support of Syrian regime leader Bashar al Assad since September 30 targeting opposition forces, while Russia said its war planes are targeting the DAESH terrorist group.