If there's one thing that makes our home planet special—other than the presence of you and me—it's water. This is The Blue Marble after all. But for something that's so characteristically Earth-y, its origins are positively extra-terrestrial.
As MinuteEarth explains, the question isn't so much whether our water came from space, but rather how it got here, what kind of space rocks it was riding on. It turns out that while there are tons of different comets and asteroids out there, flying frozen water through every corner of the galaxy, our azure lakes came from a very specific flavor of space rock.