After reading this I pictured the following.

Imagine a tube that is hexagonal in shape.

Now because the tube is at the molecular level, it's not really solid, it's more like a scaffolding, because the molecules are not solid objects, they are similar to microscopic solar systems.

Now imagine the hydrogen atom of the water molecule, flattened out like a pancake, kind of seeping through the open areas of scaffolding of the hexagonal tube. So much so, it is detected on the inside & outside of the tube.

I have no idea if this vision is correct, but it seems logical.