There was a washer and/or dryer in most of the albergues/hostels where I stayed. Most of the time they each cost between 2 and 4 Euros. I washed my running clothes almost every day by combining my things with other pilgrims’—meaning I rarely paid more than 50 cents.
Booking Albergues in Advance
If you do the Camino in the summer, there’s a possibility that there will be fiestas scheduled on days you’re planning to go through certain towns. It’s worth looking ahead at least a day or two and discussing the situation with other pilgrims. If you have the Buen Camino app, it’s easy to find the phone numbers of all the albergues/hostels in the next town, and it may ease your mind to go ahead and book things ahead when you can (though note that’s rarely possible for the public albergues, which are first come, first served).
I didn’t discover how easy it is to use Correos (the Spanish post office) to ship your backpack until well into my journey. For only 5 Euros (more if you are going farther), they will come pick up your backpack from your albergue in the morning (8:00am, though you don’t have to be there) and drop it at your next albergue by 3:00pm at the latest (usually earlier in my experience). All you have to do is visit their website, fill out a simple form, pay online, and you’re all set.
If I hadn’t fallen and hurt my ribs, I probably would have just kept running with my backpack, as it was quite small and I liked being certain of having all my things with me when I arrived in the next town, and also liked being as flexible as possible. On the other hand, for someone like my friend Lars, who only ran on some days and was carrying a very large backpack, Correos was ideal. You could easily use it the entire Camino or just on some of the tougher days.