Almost everything i've read says urine is safe for the short term unless you have a UTI or similar. As your livers job is to filter things...so urine is sterile, granted the army says it can have up to 2% salt(which your body may need anyway depending on the region) it can still help you survive. You like real life situations so lets go real life
"in 2008, a Chinese man by the name of Shen Peiyun survived six days by laying still and drinking his own urine, which is solid evidence that it won't kill you at least some of the time. While it is not necessarily fatal, it doesn't mean it isn't harmful. For instance, in the case above, no expert has asserted that he would have died without drinking his own urine."
If you go by the rules of 3, then after 3 days he should of been done with no water, yet he lasted 6 days.
http://listverse.files.wordpress.com...pg?w=363&h=400
“If you have to [drink urine], I suggest you let it cool down first. It doesn’t taste very nice.”
"Ricky Megee stopped to help a couple whose car had broken down. Next, he was waking up with rocks and dirt covering him. The pit was meant to be his final resting place. He claimed to have been drugged and robbed by the couple. Megee suffered from exposure and malnutrition for the next two months. His diet consisted of leeches, lizards, insects, frogs, and snakes. He was forced to drink his urine when he couldn’t find rain puddles to drink from. He weighed 230 pounds before he got lost and weighed 105 pounds at his rescue. The man who found and rescued him described him as a walking skeleton."