Can you make clothing that is no longer waterproof 100% water-resistant again by waterproofing it? Clothing that is no longer waterproof cannot be made 100% so again, even with waterproofing. Related articles When should I waterproof functional clothing? What sizes are Engelbert Strauss shirts? Which detergent is suitable for caring for functional clothing? How do I wash care clothing? What is important to remember when caring for high-visibility clothing?