Heat a grill or grill pan over medium-high heat. Grill the pineapples for about 5 minutes on each side or until char marks appear. Set aside and let cool.
In a large pitcher, combine water and sugar. Stir until the sugar is dissolved.
Process the pineapple and lemon juice in a blender until smooth.
Pour pineapple mixture through a strainer into the pitcher with the sugar mixture. Stir well and serve over ice. Garnish with a wedge of grilled pineapple.