You can remove the mirror from its base to fill and empty the water, or you can leave it on the base to fill and empty the water because the mirror can be swiveled completely upside down. The base, however, stays permanently affixed to the wall.
I saw other reviews talking about how the adhesive is not very strong. As my shower walls are very flat and made of plastic, it seems to be stuck on there pretty well. I do not know how well the adhesive would stick to tile or other shower wall materials. I did make sure I cleaned the wall with alcohol to make sure the adhesive could have its best chance of sticking.
Please see the attached pictures and videos:
1. Video of the hot water filling up the hollow space behind the mirror and of the mirror being rotated upside down to drain the water in between uses
(I leave the mirror attached to the base and upside down after draining to make sure standing water doesn't build up)
2. Top back view of the mirror (you can see the hollow space behind the mirror)
3. Photo where you can see the mirror "as is" with no water in it. It's fully fogged up and you can't even see the pink razor in the reflection.
4. Top front view of the mirror (where the water goes)
5. This picture shows the mirror after being filled with water and remaining fog-free
(it's hard to see, but you can tell that the shower curtain in the background is still foggy versus the mirror where you can see the pink razor clearly)
Hope this review helps!