1. Rub rims of 8 chilled glasses with lime wedges, and dip rims in salt to coat, if desired.
2. Stir together limeade concentrate and 3 1/2 cups cold water; add liquid from maraschino cherries.
3. Fill prepared glasses with ice. Pour limeade mixture into glasses, filling each two-thirds full; add sparkling water to fill.
Note: We tested with San Pellegrino Sparkling Natural Mineral Water.