The most durable pond liner materials are EPDM rubber, and RPE (reinforced polyethylene). EPDM rubber is durable, flexible, and resistant to UV rays and it can tolerate temperature fluctuations without becoming brittle, making it a popular choice for small ponds. However, EPDM is particularly vulnerable to punctures, making underlayment a definite necessity. The added cost of underlayment, combined with its significant weight, means it is rarely used for large installations.
RPE is a multilayer, reinforced geomembrane, which gives it remarkable strength, UV and puncture resistance, and flexibility, all in a lightweight material. RPE typically doesn't require underlayment, and can be shipped in very large panels, which makes installation fast and easy. While RPE doesn't have the long track record of EPDM, it is an affordable, extremely durable option for all pond sizes.
