Distilled water easily available?

Not silly at all. It is almost impossible to buy in some places such England. It is found in Barcelona. If you need it for a C- PSO, you do not have to use distilled water. It is used to avoid mineral build up, that’s all.

Someone should be able to tell you what its called over there.

It’s been asked and answered in these forums before. I think it’s maybe just at farmacias in Spain, but you could search the groups for previous answers with first hand knowledge.

If you are talking about distilled water for a CPAP, there is no need to buy it. There are a lot of posts here that discuss this, but you can fill the CPAP reservoir with regular water for the short amount of time you will be traveling.

The only reason people are told to use distilled water is because tap water can leave a slight mineral film over time. However, just use a clean cloth to wipe it out every few days and it will be fine. I have gone for over a month using regular tap water and mine was perfectly fine.

For a CPAP? In addition to using tap water, you could try a moisture exchange filter if your CPAP can run without the reservoir/humidifier. I’ve been using these for years when travelling and while not as good as a reservoir humidifier, they are good enough. Plus, you save volume/weight by leaving the reservoir at home. But, bring an extension cord or buy one as soon as you arrive. Spanish hotels don't always have an outlet near the bed.

I did a search for “agua destilada” and the department store El Corte Inglés sells it in its supermarket section. In Barcelona there’s one at Plaça de Catalunya and the supermarket is on the lower level.

jaimeelsabio...

Good job. Problem solving at its best!

Yep, one can get "aigua destil·lada" (in Catalan, the local language) --pronounciation is roughly "ah-ee-goo-ah-dust-tea-lah-dah)-- or "agua destilada" (in Spanish) in many supermarkets and hardware stores.

Something to mention is that Barcelona is located in an area with very hard water and while is perfectly safe to drink tap water, it contains lots of minerals (See my post at https://community.ricksteves.com/travel-forum/spain/tap-water-vs-bottled-76ba8837-6dc4-40ed-bc7a-d32036095a7a). Hardness contributes to the presence of limescale so it might not mix well with equipment such as CPAP

Enjoy!