As the sound of bombs becomes a distant echo, many refugees from Syria's war face a new enemy: thirst. For some, the battle begins the moment they reach the border of water-scarce countries such as Jordan and Lebanon.

"We didn't want to end up in a camp," said Fahid, who attempted to enter Jordan illegally with his wife and children and spoke to Al Jazeera under a pseudonym. "My children asked for a drink, many times, but we had nothing left. We fled with very little."

Fahid's family of seven, afraid of being resettled in isolation, endured several gruelling days without water in the barren border region connecting Syria and Jordan. They were later assisted by a humanitarian aid group and brought to al-Azraq refugee camp, where water is still in slim supply.

Water scarcity is a stark reality across the Middle East. According to Salman Zafar, founder of EcoMENA, the region is home to 6.3 percent of world's population, but has access to only 1.4 percent of the world's renewable fresh water.

"Around 45 million people lack access to drinkable water in the Middle East," said Clint Borgen, president of The Borgen Project advocacy group. The most vulnerable are those without a permanent residence or who fall below the poverty line, including a high percentage of Syrian refugees.

Since the start of the conflict, more than five million Syrians have fled their war-torn country. Many have sought refuge in neighbouring countries whose water challenges predate the Syrian crisis.

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Currently, 1.4 million Syrians live in Jordan, while another 1.5 million have resettled in Lebanon. Both countries have historically struggled with seasonal water shortages, low investment in infrastructure, and poor management of water resources. The dramatic population increases have added another layer of stress, with demand for water rising by 22 and 28 percent respectively in Jordan and Lebanon since the Syrian crisis started.

Population growth in Jordan has reduced the average amount of fresh water available for each person to less than 150 cubic metres annually, much lower than the 500 cubic metres that mark water scarcity by United Nations estimates. The average water availability for United States citizens, in comparison, is more than 9,000 cubic metres a year.

Lebanon had been considered one of the few countries in the region with a relatively adequate supply of water. But although the daily per capita share is estimated to be around 145 litres, more than double Jordan's output, population pressure has degraded basic municipal services, leaving many without access to water and contaminating existing supplies.

"For refugees living in camps, where all services are provided for, the average amount of water access per day is 35 litres," Soman Moodley, Oxfam's policy adviser in Jordan, told Al Jazeera.

The UN estimates that only one in 10 Syrian refugees live in camps where humanitarian aid is available. Outside of the camps, 93 percent of Syrians in Jordan live under the poverty line. In Lebanon, which has no official refugee camps, more than 71 percent of Syrians live in poverty.

Families often establish makeshift camps or find shelter in derelict, abandoned buildings, without heat or running water. They cannot afford rent, let alone the cost of tanks and weekly refills. For the poorest, who sometimes siphon illegally from their neighbours, water shortages have reached emergency levels, as low as one litre a person per day in some areas.

"In certain areas where Syrians gather, they are drinking unsafe water," Mohammad Shakir, a representative with Islamic Relief Worldwide, told Al Jazeera.

Some of Lebanon's streams, typical sites where Syrian refugees set up informal camps, are heavily polluted with pesticides and sewage. One Syrian woman, living at Shatila refugee camp in Beirut's southern suburbs, described the water there as "hell water", noting it was so contaminated that it began to degrade metal cutlery within minutes.

Another refugee living in the Bekaa Valley, who spoke to Al Jazeera on condition of anonymity, said that water from their 5,000-litre tank shared between three families "is drinkable, but [we] cannot just use it to drink. We have to use it to clean, to wash, everything. [We] have this water for three families and it is not enough."

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Poverty-stricken and often living without legal status, some Syrian refugees have resorted to roaming the countryside, erecting tents near farms and moving with the start and end of harvest seasons. They obtain water from irrigation systems and wells.

"You do have refugees who continuously move around. They stay in agricultural areas where they know water will be a bit easier for them to get," said Rita Zawaideh, founder of the Salaam Cultural Museum, which leads medical humanitarian missions for Syrian refugees.

There are even instances where Syrian refugees have been forced to relocate to other countries due to endemic water shortages: "I recently heard a story of a young family who relocated to Jordan and was forced to relocate again to South America because of the conditions, specifically lack of water," Zafar said.

Moodley said there is a desperate need for governments around the world to step up and provide increased aid and development funding to meet the needs of both refugees and local communities, including adequate water supplies.