Getting water day after day to the tens of thousands of refugees stranded in the sweltering desert of Niger due to attacks by Boko Haram Islamists is nothing less than a Herculean task.

More than 50,000 people abandoned their homes early this month to flee to dusty camps in southeast Niger after a major attack June 3 by the jihadists from neighbouring Nigeria against the town of Bosso, near the border.

"People must have water, it's a fundamental necessity. You can go two days without eating, but if you're severely dehydrated, you die immediately," said Mohamed Ali, in charge of water supplies for the UN Children's Fund (UNICEF) in the Diffa region.

UNICEF ferries 280,000 litres (61,600 gallons) each day to the Kidjendi camp, where about 40,000 people are housed -- with help from NGOs such as Acted and the International Rescue Committee.

A further 60,000 litres too have to be moved daily to a camp for the displaced at Gari Wazam, which hosts 25,000 more people.

"Tomorrow we have to start all over again," says Ali after the day's work is completed.

Even tanker trucks used to transport oil have been coopted into humanitarian service to keep the refugees alive, with one reading: "Warning: flammable liquid".

The lorries ply incessantly back and forth between water supply points and distribution centres and have been fitted out by aid workers with "Bladders", large flexible plastic tanks fitted with taps.

- 'Hard to get water' -

Along Highway 1 north of Diffa, orange jerrycans have been lined up by the hundreds amid an ocean of tents and straw huts in anticipation of the arrival of the lorries.

"There are many people. You can come with two jerrycans, but you may find you can only fill one up," says Cheldou Malou, a 25-year-old with five children who lives with a further seven people including her husband and two elderly men.

"There are too many people, it's hard to get water... Sometimes you have to come back in the afternoon," she says.

Fetching water is mostly women's work, as in many African countries. Clad in worn and colourful clothes, they balance hefty loads on their heads.

Some women are very young, like Falimata Koderam, who is 16 with no children, and Hatcha Halima, 20, with three children. "It's heavy, but we're used to it," they giggle when asked why there are so few men in the queue.

The two girls have been in the camp for a fortnight and would like to go back to Yebi, their village near Bosso. They say it can be hard to obtain food in the camp.

- Wary of queue jumpers -

Men are tasked with finding money for food and firewood, but they too sometimes have to queue, like Mamadou Chiari, a farmer from near Bosso, married with five children, including a one-year-old baby.

In general, camp residents put their jerrycans out in the evening or at dawn and return once a tanker truck arrives.

The plastic containers look almost identical, but everybody identifies their own by a coloured tie of cloth, a scratch mark or a touch of paint. They are wary of queue jumpers and con artists.

"Sometimes there are problems. Some people think they are more cunning than the rest of us," Chiari says. "We settle matters by talking them through."

He "manages to earn a little money to feed the family. You can be a removal man to move somebody's things or you can help out a herder by keeping an eye on his animals."

Giant-horned Kuri cattle native to the Lake Chad region stray through the camps. Many herders fled lakeside territory and cohabitation between man and beast can be problematic. The animals also need water, but their excrement has contaminated ground water in places where it is too shallow, making a number of wells useless.

Aid workers have set out to deal with the difficulty by making "pastoral wells" to draw the beasts away from settled areas. They are seeking suitable places to put up pumps for drinking water so that there is less of a need to transport it.

"This is a business that is very expensive," Mohamed Ali says. "I'm sure that we're going to exhaust all our financial resources. We're going to need more resources."