Since I travelled to Galicia this past weekend, I heard both Galician and Galego, which is a different language from that region. It sounds similar to Spanish, but you can take whole language classes that will show you the difference! It is a co-official language in the region along with Spanish. For example, they say Boa Tarde (good afternoon) or Boa día (good morning) as greetings.
Throughout all of Spain, the Euro is used as currency. The exchange rate can fluctuate, but currently, one Euro is worth one US dollar and five cents. When I came to Spain, the Euro was stronger and was worth about one dollar and ten cents.
The cost for a bottle of water really depends on where you buy the water! The cheapest water bottle would definitely be found in a supermarket like Mercadona and will cost you about €0.25. The most I have paid for a bottle of water is about €3 but that was in a restaurant! Typically, in an alimentacion (convenience store), a water bottle will be between €1.50 and €2.00.
