It's a rude awakening. You turn the shower knob to hot, anticipating a steamy cascade, and are met with an icy jolt. Or you start the dishwasher and hear the unsettling sound of a cold-water cycle. Suddenly, the simple, comforting rhythm of your day is broken. A lack of hot water is more than a minor inconvenience; it's a disruption to your hygiene, your chores, and your basic comfort. In an...