In most Russian apartments the bathtub is located in a room next to, but separate from, the room that has the toilet. Since bathtub in Russian is ванна, the room that contains it is called a ванная. Ванная is a deadjectival noun; that is, it is an adjective in form, but a noun in meaning, so it declines like this:

Now, we are going to have a bit of a translation problem here. In the US the word bathroom means the room that contains the toilet. (It might be different in the UK...) I just asked a buddy of mine “What do you call a room in America that has a bathtub but not a toilet?” He looked at me with incredulity, as if I were an American manqué, and said “I don't know. I have never encountered the situation.” ‘Washroom’ doesn't work, because it, too, implies a toilet, as do john, head, wc, powder room, restroom and lavatory. So for the purposes of this blog entry I will call it the “bathtub room.” That sounds odd in American English, so if you are a Russian reading this blog, don't use the phrase yourself; just understand that we are making do. That said, here are some sample sentences: