It is pretty clear that planet formation also includes the production of water as well. I will go a lot further than that. Most of that water is subsumed in the planet's crust in most cases. Without an atmosphere, any surface water is disassociated into free hydrogen which may well escape.
Earth Isn't the Only Ocean World in the Solar System
Watery worlds like Ceres — a dwarf planet in the asteroid belt — hint that our solar system is wetter than we thought. And where there's water, there might be life.
By Eric Betz
The icy dwarf planet Ceres appears to hold a subsurface sea. This discovery fuels the hunt for life beyond Earth. (Credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA)