Why Are Flexible Pond Liners Better?
When you can’t rely on the soil itself to hold water, you have three main options for lining your farm pond. Clay liners require a lot of labor to install, cost more per square foot than most flexible liners, and experience a relatively high rate of failure. Concrete is even more expensive, can release chemicals that interfere with water quality, and can crack easily in areas with low winter temperatures. Flexible pond liners are the most affordable way to line the average farm pond. If there’s an issue with the installation, the material is flexible enough to easily fix. Flexible pond liners also make cleaning and treating the pond simple.
How to Choose the Right Pond Liner
Even after you settle on flexible pond liner, you still have many options to choose from for a farm pond. Flexible liners vary in price, quality, flexibility, seam sealing difficulty, and overall lifespan. Some pond liners are better for cold environments where low temperatures make plastics brittle, while others can handle intense daily sun exposure without breaking down.
PVC liners are popular and widely available, but they’re often not a good choice for fish or plant growth in the pond due to toxic plasticizers that leech into the water. UV degradation is also a bigger problem for PVC than for other materials. EPDM liners tend to last the longest in both cold and direct sun environments. However, the seams are harder to seal with this material, limiting pond shape and size options. Butyl plastics are great for making extra flexible liners that tuck into natural nooks and tight corners with easy seam sealing. It’s also safe for fish, but the lifespan in a difficult environment is often shorter than expected. Finally, reinforced polyethelyne offers a long lifetime benefit, great resistance to puncturing from rocks and roots and also comes in huge sizes for the biggest farm ponds. In addition to being very cost effective, one other major benefit is that polyethylene liners don’t release chemicals into the water which makes them both plant and fish safe.
Regardless of the type of flexible pond liner you choose, you will likely need to install an underlay material to protect the liner from the ground below. Even with hours of grading and site preparation, most in-ground ponds still have rocks, roots, and other rough materials embedded in the soil. Dragging a layer of plastic or rubber over those extrusions leads to ripped materials and complicated patching repairs. Underlay sheets are similar in many ways to the liners, but they’re tougher and better capable of preventing penetration than the surface layer. Small rips and leaks caused by rough soil usually aren’t discovered until well after a pond is finished and filled. Since emptying a pond and repairing it can take weeks, it’s worth the cost of underlay materials to prevent even the smallest leaks. Underlay geotextiles and supportive grids can also help with sandy or gravel-heavy soils that are too loose to properly support the weight and pressure of a fully filled pond.
