East of the capital, clashes broke out in the Marj district despite a ceasefire in force since December 30.
Damascus has been without water from Wadi Barada, a once popular hill station northwest of the capital, since December 22, leaving some 5.5 million people thirsty.
The United Nations warned on Thursday that sabotaging water supplies is a war crime.
Government aircraft dropped at least 10 barrel bombs, crude munitions notorious for the indiscriminate casualties they cause, the Syrian Observatory for Human Rights said.
A child was killed as clashes resumed in the area between pro-government forces and rebel fighters led by the jihadist Fateh al-Sham Front.
East of the capital, clashes broke out in the Marj district despite a ceasefire in force since December 30. Three people were killed, one of them a child.
In Damascus, there were a number of casualties from rebel rocket fire.
Fateh al-Sham, formerly known as Al-Nusra Front, was Al-Qaeda's Syrian affiliate and remains blacklisted as a terror group by the United Nations and Western governments.
Along with its jihadist rival, the Islamic State group, it is not party to the week-old ceasefire brokered by Russia and Turkey.