In every of the European countries I've been to, every time I go to a nice restaurant I've been asked whether I wanted my mineral water plain or fizzy. The less nice places might bring you tap water by default (which is generally perfectly fine and safe).
Some eco-friendly system places here in Copenhagen now have their own water filtration system and make higher-quality still and fizzy water on site.
An aside, if in a high altitude country that speaks Spanish, if you learn nothing else, learn the difference between aqua sin gas and aqua con gas (excuse my possibly incorrect spelling). The resulting explosion marks you as a tourist for the rest of the day.
Some eco-friendly system places here in Copenhagen now have their own water filtration system and make higher-quality still and fizzy water on site.