EPDM is fish safe, and less vulnerable to UV exposure than other materials found in most pond liners. This makes it a very popular option for water features that intend to support a full ecosystem. There are no plasticizers or chemicals that will leach out into the water and poison the residents within.
EPDM is incredibly flexible and soft, making it a popular choice for custom-shaped ponds. It's also highly reliable in extreme temperatures, making it an all-season solution.