In a small saucepan combine sugar and 1 cup of water. Bring to a boil and stir until the sugar has dissolved. Allow the mixture to cool to room temperature, and cover and refrigerate until chilled.
Squeeze lemon juice from fresh lemons and remove the seeds from the juice (leaving the pulp). In a pitcher stir together syrup, lemon juice and remaining 7 cups of water. Add ice and lemon slices and serve cold.