Maybe he believed in urine therapy. There is a group of people in this world who believe urine to be a panacea which can cure any illness, reverse aging, and make you more beautiful.

I think people make assumptions based on the fact that Urine (from a healthy person) is sterile...either that or they've been watching Bear Grylls drink his own wee. It can be proven that drinking (healthy) urine is NOT harmful to your body...as long as you're drinking enough water to counter the salt. What you might read about urine being full of 'poisons' isn't true unless the person expelling the urine is sick (or especially if they have a bladder infection). All that aside, there's absolutely no scientific benefit to ingesting the stuff.

The truth is that the salts and minerals in the urine act like a diuretic. In a person who hasn't had much to drink the urine will be thick and dark containing even more sodium and salts. This is going to cause the person to urinate more and even though urine is mostly water, there will be a net loss of H2O in the system. This is why it's so strongly ill advised in a survival situation. Even if dehydrated diuretics will force your kidneys to make pee stealing from the water reserves in your blood.

One other thing that's usually not considered is eating. Your body needs water to digest food. If you eat and don't drink, you're going to dehydrate that much faster...and if the food is high in sodium or caffeine, it's going to be worse. I recently flipped over a package of my favorite freeze dried hiking food. 2 servings, 500 calories, over 1000mg of sodium per serving. If you eat the whole bag like I do that's almost 100% of your daily intake of sodium in one sitting! I don't buy that brand anymore.