Canadian researcher William Sommers found that these wild camels had the ability to drink saltwater slush, although it is not yet certain the camel can extract useful water from it. Domesticated camels do not attempt to drink salt water, though the reason is unknown.

http://en.wikipedia.org/wiki/Bactrian_Camel

In general, the water in the Eastern Province would be considered unfit for drinking according to the American sanitary codes which considered 500 parts per million of salt as the absolute maximum that should be found in drinking water. In Arabia, water with 1,000 parts per million was regarded as practically rain water. We commonly drank water with as much as 3,000 parts per million; at one well, we saw some small Bedouin boys drinking water that was later analyzed at 10,000 parts per million. Seawater is slightly more than 30,000 parts per million, so these young men were drinking water that was a third as salty as seawater. When confronted with a well too bitter to drink, the Bedu let the camels drink it and then they drank camel's milk. Among its many attributes, the camel also acted as a walking still.
http://www.saudicaves.com/blue/Outnblue.htm