When travelling, we like to be able to buy a few items at a local grocery (mainly water, for…read morerefilling our bottles for day-trips, etc.; we also get fruit). These aren't items we can really bring along from home, so depending on our destination, local stores may not be abundant.
I had no idea what we'd find in urban Paris. However, we ran across FranPrix while waiting for a restaurant to open. After buying some water and lugging it almost a half mile back to the hotel, I then found this location about a block from the hotel. Oh well.
I did not shop here extensively, but we made use of it one morning to pick up a couple of items. They opened at 8 a.m. These are space-limited urban stores, not some 2-acre suburban American mega store. Understand that going in, and set expectations accordingly. I don't mean that in a bad way; they seemed to make decent use of the space they had, and their selection was fine. I was happy to find this chain existed.
These seemed pretty common, so there could be one near your hotel or near close Metro stop.