I'm wondering whether it's possible to survive most fires by filling the bath with water and a ballon with air (it doesn't matter if it comes from human exhalation), then go underwater and breath through the balloon. When I was a kid I used to breath in a ballon that I would fill with air by exhalation. I could hold for 10-15 minutes easily and would stop by boredom, I never felt like I was about to miss oxygen. I don't know whether this strategy has ever been tried before. Are you aware of any such case? It might be hard to stay underwater due to buoyancy. Also, I don't know how hot would the bath be when there's fire all over it (with and without water still flooding the bath).