In a small sauce pot combine water and honey. Set over medium heat.Stir until honey dissolves into water.Remove from heat and allow to cool to room temperature.
For the cocktail:
Place salt on a small plate. Moisten the rim of serving glass with grapefruit rind.Twist glass around to thoroughly salt the rim. Fill serving glass 2/3 full with ice.
Combine grapefruit juice, lime juice, honey syrup, tequila and club soda in a shaker or other vessel.
Pour into glass. Add more ice if necessary. Garnish with grapefruit wedge.