Don't bring a bottle to the Camino
You might be tempted to bring a fancy water bottle to the Camino. Don’t.
First, don’t be fooled by the “environmentally friendly” argument. It’s B.S. Very few bottles survive the Camino, meaning you’ll discard them on or after the Camino anyway, throwing 30 € and a thick-walled piece of plastic into the trash.
Secondly, every(!) pilgrim buys a bottle of water at some point. Maybe it’s because the next leg has infamously foul tasting water fountains (most of La Rioja) or because water all the time isn’t fun. You’ll pass a supermarket every few hours, if that, so just stop there. Start in Saint-Jean-Pied-de-Port and keep the bottle. Use it until it gives up, which is usually after 200 kilometers or so, and just recycle it and buy a new one. Recycling bins are in every town you’ll pass.
Not only will you get much more bang for your buck and don’t bring plastic into the country (imagine 200’000 bottles brought in by pilgrims every year), you’ll also have a little variety in your drinking, which is a happy thing to happen.