When we went to France my HV recommended Evian as it has lower salt levels. DD was 6 months and exclusively breast fed and as it turned out we did not need the 10 bottles I packed as it rained and was quite chilly!
I think I remember the sodium levels need to be under 10 per whatever the unit is they use as a standard. Sorry-vague as but once you look at a bottle all will be clear . We found shop own brands varied enormously in France. Evian I guess is the better known brand, but we couldn't always find it in the local supermarkets so used own brand. DD was 10 months but we had no probs.