Rinse 1 cup fresh pine needles under cool water and pat dry.

Bring 4 cups of filtered water to a boil in a small saucepan over high heat.

Blanch the pine needles by submerging them in boiling water for 30 seconds, then remove with a slotted spoon.

Combine the blanched needles and ginger slices in a large glass jar, pour the hot water over them, cover loosely, and steep at room temperature for 24 hours.

Line a fine mesh strainer with cheesecloth and strain the infusion into a clean container, discarding solids.

In a small saucepan over medium heat, stir together 1 cup honey or cane sugar, 1/2 teaspoon citric acid, 1/4 teaspoon sea salt, and 1 cup of strained infusion until the sweetener dissolves (about 2-3 minutes), then remove from heat.

Pour the warm syrup back into the remaining infusion, stir in 3 tablespoons fresh lemon juice, and let the concentrate cool to room temperature.

Transfer the concentrate to sterilized bottles and refrigerate for up to three weeks.

To serve, mix one part concentrate with three parts chilled carbonated water over ice and stir gently.