The prices for pond liners can vary significantly, depending on the material you’ve chosen. Some types, like very thin PVC, are made from inexpensive plastic chemicals. PVC is light, so it’s not difficult to ship, and is relatively easy to store. Because it comes in narrow rolls and usually requires that you shape it and glue sections together on-site, there is little labor involved in sending out a quick roll and letting you worry about installation. Offering a short warranty period also reduces potential claims for damage or degradation, so the 10 year warranty on PVC liners makes them relatively cheap. EPDM is a synthetic rubber, made from more expensive compounds. It’s the heaviest of the liners, which can add expense and complexity to shipping. Since it’s so unwieldy, it can be difficult to store, and even when moving equipment like forklifts are available, they’re not recommended since EPDM is extremely vulnerable to puncture damage. If shipping can be arranged at a reasonable rate, you’ll need to piece together the relatively small panels with tape. Large panels are impractical because EPDM is so heavy, manual installation would be impossible. Seams are also vulnerable to leaks, and potentially hundreds of feet of taped seams present lots of opportunities for error. But EPDM is a simple material, and more durable than PVC, so it generally shows up in the middle price range.
RPE (reinforced polyethylene) is another popular pond liner, composed of reinforced, woven sheets of HDPE (high density polyethylene) sandwiched between layers that can offer extreme UV protection, chemical resistance, flexibility, and so on. Since RPE is so durable, it is generally comparable to other liners twice as thick. For example, 30 mil RPE liners offer similar protection to 60 mil EPDM or PVC. This is important to keep in mind, since if you compare prices between 45 mil products in each class, RPE appears to be the most expensive. While the 24 mil RPE is cheaper and longer-lasting. RPE offers additional benefits as well: since it’s so light, it is easy to ship and install, very large panels can be fabricated on-site with in-factory welding if needed. The liners can be cut and shaped to your specs and shipped out within a day or two. Manual installation is much easier, since the material is not susceptible to tears or punctures like PVC and EPDM, and can easily be managed by just a few people for moderate size ponds.