Reminds me of a story Max Conrad–famous long-distance flyer–told on himself. Max had a number of world record distance flights–Casablanca to Los Angeles non-stop for example–or closed-course records for solo flight over 50 hours in a Comanche. The question most asked of him–“How do you go to the bathroom?”
Max mentioned one of his early trans-Pacific flights. I like milk. The airport diner had a dozen small cartons that they gave me. I was halfway to Hawaii before I opened the first one–it sure tasted good–I hadn’t realized how thirsty I was until I took the first drink. I thought that I’d just sweat it out–and a bit later, I drank the third, then the fourth one. By the time I was ready for the next one, the inevitable happened–I had to go. I couldn’t find my “emergency jug”, but thought “I"ll just go in the empty cartons. Hand-flying a Comanche without autopilot in the tropics PLUS the mechanics of filling the tiny carton takes ALL of your concentration! The biggest problem–How could I have more “Output” for filling the cartons than I had “Input”–all the empty cartons were full! I desperately drank another carton–it was starting to sour, but I drank it anyway, (all the while balancing the carton I was drinking, the carton I was “filling”–as well as flying the airplane)–and temporarily solved the problem–but the problem came back in half an hour.”
"I reluctantly drank the next carton–(which was getting more sour by the hour!) to make room for yet another. In addition to my normal time/speed/distance calculations, I added “range” as well–HOW MANY MORE HOURS, AND HOW MUCH MORE SOUR MILK WOULD I HAVE TO CONSUME BEFORE MAKING HAWAII? It was with tears in my eyes and holding my nose when I choked down the last carton of milk–only half an hour out of Hawaii–then RAN to the bathroom on arrival! People ask me "wouldn’t you insist on an extra engine for long overwater flights? I reply “NO BUT I DO INSIST ON REDUNDANCY IN RELIEF BOTTLES!”