Niles says aging washing-machine systems are notorious for busting when you least expect it. "A bulge in the hose line indicates it's weak and ready to go," he says. Check the hoses before you go, and turn off the water supply to the laundry area, just in case.
An aging water heater can also break down and send water cascading. "Lots of times there are signs that a water heater's failing," says Tom. "Water on the floor around it, or rust on the outside." Rust can mean that the sacrificial anode rod inside the tank has been depleted and the water is affecting the tank itself. Tom suggests checking the anode rod and turning off the water supply before you go away. "That way if your it dumps out, the only thing that happens is you get a wet basement," says Tom.