In a saucepan on the stove, combine the water, sugar, lemon zest and juice, and pine needles then bring the liquid to a boil, making sure to submerge the pine needles completely.
Reduce the heat to a simmer, cover, and cook for 1 1/2 to 2 hours, until the liquid has reduced and the needles are soft and have started to darken.
Strain the mixture to remove all pieces of needles and bark and set it aside to cool. You can keep the cordial in your refrigerator for 10-14 days.