Liners designated for ponds are generally assumed to be safe for fish and other wildlife, but it's a good idea to look for certifications indicating they're safe for both fish and plants. Some liners may have additives or coatings that make a normally safe material harmful for aquatic inhabitants. Look for high-quality liners, such as those made from RPE and EPDM that are specifically designated for aquatic environments and do not leach harmful chemicals into the water. This ensures that the habitat remains safe for fish, amphibians, and beneficial microorganisms.
Some liners, including reinforced polyethylene (RPE), are ANSI/NSF 61 certified for potable water, which is the highest safety rating available. This rating guarantees that no harmful chemicals leach from the liner over time, and the water it stores remains safe for human (and fish and plant) consumption.
