As some of you may be aware, some time back my upstairs neighbor had a leak which caused the ceiling to crash down on my water heater and made it stop working. As a result, I had quite a hassle going back and forth with my neighbor's insurance who gave me the runaround before they finally paid money toward the damages.
Fast forward, I had to replace the water heater to the tune of over $1500.00 and, in the process the plumber had to turn off my main water valve in order to do the work. I had thought that when the main water valve, in my unit, was turned off that it only affected my unit. Guess what? It also turned off the water to my upstairs neighbor and they were NOT happy!

I couldn't help but think to myself, "Now isn't that rich? YOUR leak caused damage to my water heater and YOU are going to get annoyed?"