45 Mil EPDM Fish Safe Liner with a 20 Year Limited Manufacturers Warranty. This Top Grade Tear and Puncture Resistant 45 mil EPDM liner is perfect for adding a stream or for lining your waterfall. Never settle for PVC or anything less than 45 mil EPDM PondGard Liner. Pondliner is the foundation of every great pond and specially formulated for water gardens. Don’t settle for anything but the best. Firestone Pondgard pond liner is fish safe, strong and durable yet pliable and will last you for many, many years. EPDM 45 mil is the #1 choice for contractors, landscapers and consumers that demand only the best.