I'm guessing the whole phrase 'vasca da bagno' means bathtub, while vasca alone often means sink, but its a pretty odd way to introduce the word
Bagna = bathroom Vasca = tub Vasca da bagna = bathtub Vasca per pesci = fishpond
I think that in the UK we would say "I have a bath" while "I have a bathtub" is more American
If I say "I have a bath." in American English, there would be water in the bathtub ready for me to go into. "I have a bathtub." would be the fixture that you take your bath in and it would be rather than a shower fixture.
In Australia "I have a bath" means the object in your bathroom. "I am having a bath" means you are in the bath with water. Of course, you can change the meaning by saying "I have a bath every day".
It's a long time since I posted this but I think I posted it because at the time "I have a bath" was not accepted. Likely it has changed since but I have no way of knowing as far as I can see.
I have noticed "da" is used when the word after comes attached in front of the first word in English and situation is that the word after explains which kind of the first word. For example "bathroom" is actually "stanza da bagno" but it is usually shortened to "bagno"
"location of" is using "da"
"del" is a contraction of "di" and "il", but "di" is not used for this as it is used more to say "made of" rather than explain "which kind of" or even more specifically "from where". For example "vasca della porcellana" would be a porcelain tub or a tub made of porcelain.
http://italian.about.com/library/fare/blfare153a.htm prepositional articles http://italian.about.com/library/fare/blfare114a.htm simple prepositions http://italian.about.com/od/grammar/a/italian-preposition-da.htm http://italian.about.com/library/fare/blfare157a.htm di http://italian.about.com/od/grammar/a/italian-preposition-di.htm http://italian.about.com/od/grammar/a/italian-prepositions.htm
The word for bathtub is 'vasca da bagno'. So I'm guessing in this case it's just memorization.
"Da" is used for causative forms. So, think of it less as "tub of the bath", as "vasca del bagno" would literally translate to, but more as "tub for bathing", which would be a literal translation of "vasca da bagno".
I'm having trouble understanding why "I have a bathtub" is synonymous with "I have a bathtub in the bathroom." Or, why is "vasca da bagno" not redundant?
"vasca" means "tub" and there are other kinds of tubs besides a bathtub.
"bagno" means "bath"
"stanza da bagno" means "bathroom"
"vasca da bagno" means "bathtub"
That being said, "stanza da bagno" is often shortened to "bagno" and so they can't very well shorten "vasca da bagno" to "bagno". That would be confusing. So people use tub for bathtub. That does not make it redundant if we use the whole term instead of the abbreviated term, because the abbreviated term stands for the whole term in the specific context only. Without that context, it has a broader meaning.