1Stir water, cider, maple syrup and salt in large container or stockpot until salt is dissolved. Add pork to brine mixture. Cover and refrigerate at least 8 hours but no longer than 12 hours.
2Heat coals or gas grill for direct heat. Remove pork from brine mixture; rinse thoroughly under cool running water and pat dry. Discard brine. Sprinkle pork with rosemary, pepper and garlic powder.
3Cover and grill pork over medium heat 20 to 25 minutes, turning occasionally, until pork has slight blush of pink in center and meat thermometer inserted in center reads 160ºF.