Let's ignore the planet in the middle for now and just consider a big drop of water. The mass of water is proportional to the radius cubed:
$$ M = \tfrac{4}{3} \pi r^3 \rho $$
and the surface gravitational acceleration is given by:
$$ a = \frac{GM}{r^2} $$
so substituting for $M$ we get:
$$ a = G\tfrac{4}{3} \pi \rho r $$
So the surface gravity increases as we add more water and $r$ increases. That means every extra bit of water we add is more tightly bound not less tightly bound. You could go on adding water until the whole thing eventually collapsed into a black hole, and there would never come a time when the gravity failed to hold any extra water added.
Though the working get's a little more complicated, exactly the same thing happens for a shell of water surronding a spherical body like a planet. Every additional kilogram of water is more tightly bound not less tightly bound.