Even after you realize you need to line your pond to protect it from the rigors of winter, you’re not done making decisions. Not all pond liners offer the same level of protection against winter issues. Choosing the wrong liner could leave you replacing it after just a year or two of use, especially if you’re in an area with harsh winters and extensive ice development. Make sure you’re choosing the best pond liner for the intended purpose by comparing the most common materials available on the market based on their winter durability.
Natural Clay: Poor
Leaving a pond bare, or coating it only with natural clay like bentonite, does little to protect it from winter problems. Frost cracks and heaving in the soil is practically guaranteed, unless you live in a frost-free zone. Natural clay does move around with the expansion and shrinking of the soil, but it’s not always as self-healing as advertised. Frost movements often shift clay away from one area to leave it leaking or seeping into the soil below. It’s almost impossible to pinpoint or track leaks that develop in natural clay liners, making it a frustrating task to patch them. Stick to a more reliable liner material if you’re in a cold climate.
PVC: Poor
Polyvinyl chloride (PVC) is one of the most widely sold flexible materials marketed as a pond liner. While it works fine in some applications, it’s far from the best material for most ponds. PVC doesn’t do well in cold conditions, especially when installed as a flexible pond liner. It’s more prone to cracking at higher temperatures than other polymers used for liners, making it a bad choice unless you’re in a warm environment. It’s also less durable when it comes to being stretched by soil movement due to frost heaving. Unless PVC is the only liner material available, avoid it in favor of better polymers.
EPDM: Fair to Poor
EPDM, which is short for ethylene propylene diene terpolymer, is a thick rubber material with excellent cold resistance. This alone might make it a good choice for a winter pond liner, but it has other features that detract from this benefit. First, it’s very heavy and thick when compared to other liners. This is necessary to keep it from cracking or breaking at the bends. It’s not easy to shape into the curves of an organic pond design and tends to lift or stretch instead of folding properly. It’s also hard to repair when time and wear eventually causes a leak. Finally, the material is rarely safe for fish and plants due to chemical ingredients that leach into the water. While it’s better than PVC as a cold weather pond liner, it’s not a good liner material in general.
HDPE: Good
High density polyethylene (HDPE) is available in fish-safe formulas that can withstand a wide range of freezing temperatures. However, it’s still not quite the best pond liner due to a slightly less flexible design than RPE. HDPE can freeze without losing its flexibility, something that most LDPE liners can’t do. It’s best when reinforced, but many liners made of HDPE are non-reinforced specifically because the material is fairly tough on its own. There is still a potential for rupturing and tearing when HDPE liners lose support due to soil shifting and frost heaving. For the best results in the winter, stick to RPE instead of HDPE.
LDPE: Good
Low density polyethylene (LDPE) is more flexible and easier to handle during installation, but it lacks some of the cold resistance of HDPE or RPE. It still remains flexible at cold temperatures like all polyethylene materials, which helps it resist cracking when ice forms and expands over the surface of the pond. It’s not as durable as RPE in general though, and it can be difficult to find in fish-safe forms. Only pick LDPE if RPE or HDPE isn’t available since it will likely need underlayment and other padding to protect it from tearing and ripping.
RPE: Best
For a pond that can best handle the challenges of winter, choose reinforced polyethylene (RPE) as the liner. This material combines the best of polyethylene’s flexibility when frozen and fish-safe formulation with the durability of reinforcement. Layers of HDPE and LDPE are bonded together with a reinforcing core to add tear and crack resistance for a complete package of winter resistance. RPE liners stretch enough to handle any amount of freezing and ice formation while staying strong enough to withstand frost heaving from below.
If you’re interested in durable RPE pond liners, that are capable of handling harsh winter conditions, you can find them here at BTL Liners. Our flexible liners are fish-safe, easy to install, and last longer than products made from PVC and other less than ideal materials. We can help guide you to the perfect product, for any cold climate installations, to ensure you don’t have to deal with pond leaks after the first few winters.
