Earth's water new origin

It has been commonly believed by many that Earth's water origin came from asteroids or comets. But research has shown that the Earth may have absorbed more than what we know after the impact that hit the young Earth than also formed the moon. It is believed that the Earth at that time had absorbed easily vaporized materials known as volatiles, including water and other minerals. As the moon began to form and spun, it spurned the remaining materials back into the Earth. Thus why the idea that the moon does not have any water because it was sent back to Earth.

Scientists hypothesized that when Earth was collided with a mars-sized object named Theia, it was that moment that created our moon. As such that is why we can explain that rocks on the moon are similar to those found on Earth. Same composition, but missing one thing, volatiles, which are things such as water, zinc, sodium, and potassium. The current theory is that during the collision, most of these materials were vaporized due to the immense heat and the volatiles escaped out of the system. However it is argued that the amount of material that escape would be very little due to Earth's gravity and thus be stuck around in orbit. And thus that as both of the planets are forming, they would be sharing the materials. But the problem is that the moon is constantly moving away at a rate of 4cm per year, and thus eventually be unable to accrete the materials, and thus they fall back onto the Earth.

So in the end, a new hypothosized theory of how water was formed on Earth is that it was not carried by an asteroid or comet. But rather when the collision with Theia occured, the materials within Earth was flung out, creating the moon as well as redepositing the materials back onto Earth's surface after the moon was slowly moving out of Earth's gravity field.

Sources : http://www.space.com/31115-earth-stole-moon-water.html
Sources for Theia : http://www.space.com/29047-how-moon-formed-earth-collision-theory.html