Rinse the cucumber, lemon, and ginger. Slice the cucumber and lemon into thin circles, and peel and slice the ginger.

In a small saucepan, bring 2 cups of water to a boil. Add sliced ginger to a heat-resistant pitcher and pour hot water over it. Steep for 30 minutes to 1 hour.

After steeping, add the sliced cucumber and lemon to the ginger water. Fill the pitcher with 4 cups of cold filtered water and stir gently.

Cover the pitcher and refrigerate for at least 2 hours to allow flavors to meld.

Strain the water into glasses, discarding the solids. Serve over ice and garnish if desired.