In Mosul, Iraq, up to 500,000 civilians are now without clean drinking water.

It’s a “catastrophic” water shortage for the city that has been an ISIS stronghold since June of 2014. The ongoing Battle of Mosul, which began this October, damaged the infrastructure of a city already struggling to feed itself.

Residents who will be forced to drink unclean water will risk exposure to waterborne disease like cholera and will make the war-torn city’s malnutrition concerns even worse.

The water shortage is a result of damage to a major pipeline sustained on Tuesday. What isn’t clear, however, is what side was responsible.

The pipeline, which is in the ISIS-controlled western region of Mosul, could have been an act of sabotage by the organization. That’s what municipal official Basma Basseen suggested to reporters for the Agence France Presse.

Meanwhile residents offer a conflicting report, claiming the damage was more likely caused by warplanes being used by the Iraqi military, which is being supported by Kurdish, French, British and American forces. It’s the largest government offensive in the country since 2003.

“Nearly half a million civilians, already struggling to feed themselves day to day, are now without access to clean drinking water. The impact on children, women and families will be catastrophic," said Lisa Grande, a UN humanitarian coordinator in Iraq.

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Because of the pipeline’s location in ISIS territory, repairs are being delayed indefinitely. In the meantime, residents have been drinking from alternate sources, like local wells, but say that it won’t be enough. Others will “take water from the Tigris,” Abu Ali, who lives in the city’s eastern region, told AFP. The river, which splits Mosul's East and West districts, has been polluted by oil spills in the past three months.

"Water is the most important thing. We aren't washing. We are going to catch lice and our homes are filthy," said Iman Baker, a mother of three living on the Eastern side.

A UNICEF report highlighted that the water shortage would especially impact young children, 300,000 of which will have to resort to unsafe drinking water once wells run dry.

“Children and their families are facing a horrific situation in Mosul,” said Peter Hawkins, a spokesperson for UNICEF. “Not only are they in danger of getting killed or injured in the crossfire, now potentially more than half a million people do not have safe water to drink.”

So far, the government offensive has retaken roughly 40% of Mosul in an offensive approaching its 50th day. In that time, concern for the human rights of residents caught in the crossfire has mounted. About 70,000 civilians have been displaced from the city since the offensive began, according to the UN.