Make the Lynn's Lemonade: Pour the spring water into a large glass pitcher, making sure to leave enough room for the lemons and nectar. The warmth of the water helps the agave nectar to dissolve thoroughly. You can also place the pitcher in a sunny spot for an hour or so to get the water to the right temperature for blending the ingredients. Add the agave nectar to taste, and stir until it dissolves. Roll the lemons on a hard surface to release the juice from the fruit pulp. Slice them in half, and strain the juice using a mini strainer or citrus press. Add the juice to the pitcher and stir well. Chill before serving. Makes 1 gallon.
Make the Mango Mint puree: Combine the mango, mint, agave nectar, and lemonade in a food processor or blender and blend until smooth. Transfer to a plastic squeeze bottle, and refrigerate for up to 2 days. Makes 2 cups.
Make the spritzer: Fill a Collins glass with ice. Add the rum, puree, and bitters, then top with club soda. Garnish with a lime wheel or twist, mint sprig, and an optional mango spear, and serve with a straw.