Fish and Plant Safety for Pond Liners

Pond liner selection needs the most attention when you’re planning to add fish and plants to your finished pond. These living elements are sensitive to many chemicals added to increase the UV resistance, flexibility, and durability of the liner. Many products designed for landfill or chemical containment use will sport a label claiming they are fish safe without any testing to verify this is the case. If you trust a label without testing to back up the safety of the liner, you could end up losing thousands of dollars’ worth of fish or plant stock. Learn what to look for when shopping around for a fish and plant safe pond liner you can trust.

NSF Certification

For the fastest way to check if a liner is truly fish safe or not, look for a NSF certification label on the products. This certification verifies that a liner material is safe for drinking water for people and animals, making it more than safe enough for fish and plant use. If you’re going to eat the fish in your pond rather than just admire them for their beauty, you’ll definitely need a food-safe NSF certified liner. In order to pass the certification from the National Sanitation Foundation, liners must undergo:

  • A review of the precise formulation and ingredients to determine potential toxicology
  • Audits of the plant manufacturing the material and collections of product samples
  • Intensive laboratory testing to determine what’s released in the water over long periods of time and in various conditions.

If a particular pond liner product achieves NSF certification, it’s definitely safe to trust with your fish and plants.

Avoiding Certain Materials

While practically any common pond liner material can become fish safe through careful formulation, some materials are more likely than others to cause issues with fish. For example, EPDM tends to be fish safe in almost all circumstances, while PVC is likely to contain toxic plasticizers unless it’s specifically designed for use with fish. This is also true for roof liners and plastic tarps commonly repurposed as DIY pond liners. Stick to products sold for pond use and buy directly from a manufacturer whenever possible for access to accurate information on its safety and material content.

Asking for Manufacturer Information

When in doubt about a particular liner product, don’t be afraid to contact the manufacturer and ask questions about its formulation and fish safety. Reliable pond liner manufacturers will happily answer your questions and provide information on how they design and test their products for safety. If you have trouble getting a response from a company or don’t have your questions answered satisfactorily, you can always find another source for the same materials elsewhere.

Looking for a company you can trust to provide fish safe pond liners? Turn to BTL Liners and explore our full range of products. From pond liners to greenhouse covers and tarps, you can trust BTL for safe, reliable products. Our NSF certified materials are a great choice since they work equally well for ornamental and edible aquaculture.


Chemical Resistance

On the other side of the pond design spectrum lies the chemical processing or holding pond. Unlike a fishpond that is teeming with life, the holding pond tends to be barren and require a much higher rate of chemical resistance. Leachates from the liner are rarely a problem unless they react with the wastewater, but the liners that are safe for fish may not handle the corrosive effects of constant chemical exposure. Choosing a chemical resistant pond liner takes a lot less work than finding a fish safe material since it’s relatively easy to compare materials by their resistance to corrosion.

Cleaning Up a Pond

All pond owners need to be concerned with the chemical resistance of their pond liner if they routinely drain and scrub their water feature to clean it. If you’re building a large recreational or decorative pond that you will only dredge occasionally and never scrub to a sparkling clean, you don’t really need to worry about any specific chemical resistance. Small ponds cleaned on a regular basis are exposed to cleaning chemicals that might cause the material to breakdown or peel. Bleach, acid-based mixtures, and many oils will damage EPDM and PVC liners while doing little to multi-layered RPE materials. The combination of HDPE and LDPE materials combined to create an RPE liner provides the best chemical resistance available. Sticking with some form of reinforced polyethylene (RPE) is your best option for a pond you can clean with a scrub brush and an appropriate cleaning product.


The inherent chemical resistance of the most common pond liners can vary greatly between materials. PVC has the weakest chemical resistance unless it’s coated or combined in some way with other materials. It’s prone to damage or absorption of diesel, kerosene, saltwater, and other waste products. It can handle highly acidic liquids surprisingly well. EPDM also tends to react to all of these chemicals and more; including acids. Multi-layered RPE offers the best chemical resistance in a pond liner material. Liners made from reinforced polyethylene withstand breakdown even in the toughest chemical solutions like crude oil. They’re reliable enough to use for highly toxic storage needs like coal ash and animal waste processing ponds.

Highly Challenging Environments

Many ponds used for storing or processing chemical waste also experience other challenges that can damage pond liners. Heavy equipment is often driven in and out of these ponds or along the banks to maintain the equipment processing waste from water. Waste holding facilities also tend to be built over rough or contaminated soil that is tricky to cover with a flexible liner. With the addition heat or high winds to speed up evaporation, lower quality pond liners tend to fail. Make sure the liner you select can handle all of the challenges of the installation and not just chemical exposure.

Pond liners exposed to high levels of reactive chemicals may need additional outer coatings and protective laminated layers regardless of the material used. Multi-layered RPE in particular offers more chemical resistance when reinforced since fewer weak points form from pressure points under the surface. If you’re trying to select a pond liner product for a challenging installation, you’re sure to find the perfect match at BTL Liners.

Liners by BTL

AquaArmor Pond Liner

The most versatile liner on the market today, AquaArmor maximizes protection from harmful UV rays, tear resistance and punctures that cause leaks. Simply the best liner on the market.

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