Where I'm from (Serbia) everybody says to turn off the water boiler (the container that heats up water and stores it for use in the bathroom and shower) when you take a shower or use the bathtub. They say that if the boiler becomes faulty, the current can go through it and hence the water and kill you.

Now I would understand if we used some home-made boilers that aren't insulated or such, but can this actually happen with a modern boiler? In my country this belief is some kind of a cultural thing, everyone believes it and says that they know many people who died this way, so every time we take a shower we turn off the boilers...