Travelers in certain parts of the world are usually well aware of the importance of staying hydrated. But sometimes dehydration sneaks up on you.
Once, while on a punishing guidebook research trip to Moldova during a heat wave, even though I was drinking tons of water, my sodium levels got too low and the cramps, fatigue and temporary brain damage made for a confusing and unpleasant couple of days. But then I wolfed down a giant bag of potato chips and a liter of Coke and I was good as new.
Proper dehydration, from not drinking water, will kill you much faster and unpleasant-er as this video illustrates in unsettling detail.
Also, if you reach that special stage of desperation, drinking pee while dehydrated is, cruelly, not going to help much, due to your urine’s quickly deteriorating water-to-waste ratio. So, best to not let it get that out of control.