How does an object so dry bring water to the Earth? The answer is that it does not. Water on the Earth was synthesized earlier during Earth's evolution when it was a much hotter, bigger star.
The ingredients for water on the Earth have always been on the Earth, even when it was a younger hotter star like the Sun. This is blasphemy to establishment dogma. Unfortunately establishment dogma synthesizes molecules absent activation energy. This is a big no-no!
There is no activation energy in the vacuum to sustain the synthesis of water oceans for the time required and in the volume that Earth possesses them. You need long term sustained exothermic reactions over many millions of years to create all that water! These exothermic reactions can be viewed currently in our own neighborhood, Neptune and Jupiter have turbulent atmospheres as they synthesize water form their gaseous counterparts. Chemical combination reactions on massive scales are why these ancient stars radiate more energy than they receive from the Sun. Unfortunately this is blasphemy to the cosmological religion of Big Bang and Nebular Hypothesis. Truth is they don't care for chemistry, they want pseudoscience.