Running the London Marathon should be no problem for six Maasai warriors who have come to Britain from their village of Elaui in northern Tanzania as part of a campaign to raise money to find a vital water source (www.maasaimarathon.org).

"Back at home we sometimes run for 5 or 6 days, day and night," Isaya, a young warrior clothed in a red robe and adorned with traditional beaded jewelry, told Reuters in an interview. "Twenty-six miles not far."

He and his fellow warriors, all between 20 and 25 years old, expect to reach the finish line of Sunday's race within four and a half hours.

They will run in traditional dress -- a red "shuka" blanket toga and car-tire sandals -- carrying spears and shields showing their running numbers, and will sing and dance along the 26.2 mile route through the British capital.

"And we will do the whole marathon with no water," Isaya adds. "We often travel for many days, eating only twice a day, and we have no water."

The Maasai warriors, whose role is to protect and help provide for their people, hope to raise enough money to find and access a fresh water source for their community -- something they say could cost up to 60,000 pounds ($120,000).

An estimated 500,000 to one million Maasai inhabit scattered and remote villages across northern Tanzania and southern Kenya, living a semi-nomadic existence.

But years of drought in the region around Eluai, where these six warriors live with their elders and children, is killing their cattle and threatening their way of life with disease and famine.

Two thirds of the children born in Eluai die before they reach the age of five.

"It is a large village which has a very bad lack of water. We have only one small dam and the water from it runs out very quickly," said Isaya.

"It is affecting our people. Our children are dying. We are infected with disease from water which is dark and dirty. We sometimes have years with no rain."

Paul Martin, an expedition leader with the Greenforce charity which has been working with the Maasai since 2005, said ground surveys of the area around Eluai had found an underground water source which could offer the Maasai a lifeline.

"It's an enormously difficult and expensive procedure, but it's so desperately needed that we have to make sure we get something out of there, even if we have to go down to depths of 100 meters

"The Maasai are a proud people ... If they achieve this, they will return to their village as heroes," he said.

And Isaya has no doubt he and his fellow runners will do it.

"The finish line for us is not at the end of the race, it is when we can turn on a tap in Eluai," he said. "I really believe that can happen."