1. Cut the ginger into thin slices (no need to peel). In a small saucepan, bring the water, sugar, and ginger slices to a boil.
2. Remove from heat and cover. Steep for 30 minutes to 1 hour.
3. Strain the ginger pieces from the sugar syrup and mix the ginger-infused syrup with the fresh lemon juice in a pitcher. Chill thoroughly. Serve with plenty of ice.