Not just salty water but saline solution made with Maldon natural sea salt blended with spring water and then filtered prior to bottling and hand-labeling...
While I'll have to experiment with making my own over here in the US, I heartily support the occasional addition of salt to cocktails, desserts, etc., for enhancing flavors. Just as in the fairy tales (Cap O' Rushes for one), a pinch of salt can make all the difference.