We have found that for 90% of water feature construction, 45mil fish-safe EPDM rubber lining is the best choice. EPDM liner is flexible and easy to install. It is also guaranteed against defects by the manufacturer for 20 years. Furthermore, we cover our liners completely with tons of boulders and gravel. This not only gives the appearance of a stream bottom, but also prevents UV light from degrading the liner (especially advantageous in sunny areas). A successful pond begins with the base... Don't cut corners!    - Aquascape Design, Inc.
 

This soft polyethylene fabric will last 20 years under your liner. It protects the liner from being damaged by rocks or other sharp objects. Rocky areas may need more than one layer for maximum protection. It spreads easily and in any pond shape. This soft, polyethylene fabric will last 20+ years under your liner. It is a 3-dimensional underlayment that allows gas to escape. It has a non-slippery surface and provides protection for the liner from rocks and other sharp objects, spreads easily, and saves time compared to using newspaper or sand.