I have such a hard time buying the theory that we got our water from comet impacts. That would be a BUNCH of comets I would think. Then again, maybe we were hit by A LOT of comets.... lol
Look at the lunar surface, it’s completely covered with evidence of massive impacts ....We too have been hit many times in the past by large objects, but since our surface changes, it hides or covers up many of these impacts.
Unless the water is manufactured by the Earth itself, there’s no alternative.