Gore-tex and any breathable fabrics need the water repellency renewed every so often. NikWax is the treatment of choice, recommended by most manufacturers. Also remember never to wash breathable fabrics in detergent. Use soap such as Dr. Bronner's, shaved castile soap or NikWax Tech Wash. If you've already used detergent on it, you can remove the residues by washing once or twice in soap.