Humidity in the Formicarium

[Zintarloc]

Hello, I don't have any ants yet, I am planning on getting a queen during the next Nuptial flight next year for camponotus herculeanus (The only kind we have in Alaska). But I do lots of craft work, I weld, I do carpentry, masonry all the such but I am curious on how the what is called "water den" works. I have seen them and they are completely separated from the rest of the formicarium and the ants don't have access to it. Like the hybrid nest has the cotton balls under it and everything and I am just curious to the science of that so I can understand how to make the formicarium.

[AntsLuxembourg]

I would say that the water condenses on the walls and the ants are licking it up or they can still drink a little bit from the cotton underneath.