Fighting between the Syrian army and jihadi rebels has engulfed the source of any population's most valuable resource: water. The al-Fija spring in Wadi Barada, northwest of Damascus, provides nearly two-thirds of the city's potable water. Whoever controls the area indirectly controls the lives of the millions of people living in and around the Syrian capital.

Rebels have occupied the region for months. The pumps at the Wadi Barada water plant were damaged in the last weeks, and water that remained flowing has been contaminated with diesel fuel. More than 5.5 million people in the greater Damascus area have been partly or completely cut off from their water supply, according to UN estimates. This has forced them to search for other sources and tripled the cost of bottled water, city residents reported.

The damage could be "because of fighting, or because of sabotage or because of both," said Jan Egeland, a special adviser on Syria for the United Nations. He was unable to say exactly which side was at fault, and both government and rebel forces have denied responsibility, blaming the other side instead.

Internet research

Bellingcat, an open-source investigative journalism platform, has been documenting the damage, and suggests who may be responsible. Previously, the platform, initiated by blogger and internet journalist Eliot Higgins, has been credited with being the first to uncover the Syrian government's use of cluster bombs and chemical weapons. It has also investigated the downing of MH-17 over eastern Ukraine in July, 2014.

The analysis of damage done to the al-Fija springs has relied largely on numerous videos from the area uploaded by eyewitnesses. Bellingcat has cross-referenced them to minimize the risk of misinterpreting what they show.

The water supply was interrupted on December 23, according to the video accounts, the day the Syrian army tried to wrest control of the area from the rebels who had held it for months. The latter have proven unassailable, having mined the water plant and threatened to destroy it or contaminate the water if attacked. Either outcome would expose Damascus residents to serious harm. On a number of occasions, including for several days in July of last year, rebels reportedly cut water to the city to demonstrate the seriousness of their threats. Had the rebels made good on destroying the plant, the Syrian army would have had no further reason to hold back on attacking them.

Bellingcat: Syrian army to blame

Videos from December 23 show the facility intact, then damaged after that date. This has led Bellingcat to cast blame on the Syrian army. Another video shows a bomb impact within 80 meters (87 yards) of the water source, although the date of the video cannot be verified. An additional video shows an attack directly on part of the water plant.

"Depending on the fuse, the bomb probably exploded somewhere within the plant," Bellingcat concluded. "This resulted in widespread damage in the middle of the plant's roof." The facility's diesel generators were likely also damaged, which would explain the diesel contamination of the water.

Rebels uploaded a video on December 25 to announce the destruction of the water pipeline to Damascus. However, no other internet evidence has been found to indicate they actually carried it out.

Bellingcat's researchers maintain that the damage to the water facility was the result of the Syrian army attack two days earlier. That is the "most likely scenario," they said, including the diesel leak from a "destroyed tank, generator or another source."

Ongoing debate

Not everyone is convinced. Within two days of Bellingcat's January 4 report, more than 70 entries were posted examining the findings, including claims that there were no generators to be damaged near the Fija springs, which rely on gravity rather than electrical power to flow.

The debate over the cause continues, while Damascus residents remain without a secure supply of clean water.