Pure water yes, high ph tap water and low ph rain not so much.
The impurities left behind when this kind of water evaporates will cause problems later on. Some of these residuals are also conductive to electricity.
The short answer, always keep electronics dry.
...and as you said, if an accident does occur, resit the urge to turn it on "to see if it still works" and remove the battery or power source immediately.
A chaser of denatured alcohol before drying has also been known to help in some cases. However this may also attack glues and soft plastic components.