Just to add a bit more, the ice sublimates (loosely, “evaporates”) very quickly, meters per day.

There’s a source here on sublimation of ice in a vacuum

New estimates for the sublimation rate for ice on the Moon

As you see, at room temperature it goes up to kilograms per hour at room temperature. I’m not sure what the exact figure is, but I know how to work it out for liquid water, calculation indented

With surface temperature of 273.15 °K (0 °C) and using the equation for mass loss of liquid water in a vacuum of

(pe/7.2) * sqrt (M/T) kg / m² / sec (equation 3.26 from Modern Vacuum Physics)

where M is the molar mass, 0.018 kg for water, T is the temperature in kelvin, pe is the vapour pressure, which for water at 0 °C (273.15 °K) is 611.3 Pa, (Vapour pressure of water at 0 °C), so putting all those into the formula we get:

(611.3/7.2) * sqrt(0.018/273.15) = 0.689 kg / m² / sec.

So you lose 24*60*60*0.689 or about 59.529 tons a day from each square meter surface of water.

Compare calculation results here: Modern Vacuum Physics where they use the vapour pressure for water at room temperature 295 K to calculate (2300/7.2) * sqrt(0.018/295) = 2.495 kg / m² / sec.

So at room temperature you lose 24*60*60*2.495 or about 215.6 tons a day from each square meter surface of water.

So at 0 C you’d still lose about 60 meters of water a day subliming into space.

I don’t know if the transition from ice to water makes a difference, but probably not that much. They use ice sublimators for spacesuits so it should be possible to find the figures for ice.

See also my Do water planets exist? - I found this question while researching for an update of my answer there.

It’s also relevant to the idea of liquid airlocks on the Moon. You can’t use liquid water but you could use ionic fluids. Same also for liquid mirror telescopes on the Moon. They would probably use ionic fluids too.

See also:

• Liquid airlock
• Ideal location for radio, infrared telescopes and other observatories

in my Case For Moon First