Safe Waters
One of the defining characteristics of reinforced polyethylene geomembranes is their impermeability to liquids of all types. This makes them ideal for use in applications where the primary mission is to contain water. Because RPE is remarkably affordable, easy to ship, and easy to install, it’s appropriate for both small and large applications. In fact, RPE is a widely used material for use in everything from backyard garden ponds to artificial lakes, reservoirs, rivers, and golf course water features. RPE liners are so durable and resistant to punctures that they may not even require underlayment in installations where the underlying surface is free of stones, tree roots, and other obvious potential hazards.
Whether you’re installing an artificial waterfall that you’re expecting to enjoy for decades, or building an artificial lake intended for a community recreation center, a liner that’s durable enough to last for seasons of varying weather and daily wear and tear is an absolute necessity. RPE liners make excellent candidates for these installations. Even large installations are easy and reliable since RPE can be produced and shipped in extremely large panels and most seams can be sealed in the factory where top quality can be assured and verified. Fewer seams mean fewer points of vulnerability, especially over years of use.
RPE liners are also suitable in more specialized applications, particularly those involved in food production, where potable water certification is valuable. Aquaculture involves the production of aquatic animals and plants for human consumption. These might include seaweed, fish, crustaceans, and shellfish. RPE liners are usually involved in land-based aquaculture operations, where they may line fish nurseries, shrimp ponds, and raceway ponds. In aquaculture and other food operations, sanitation and regular disinfection is necessary, it’s important to have a liner that’s durable enough to stand up to repeated exposure to disinfecting products and regular cleaning procedures. A liner with a tendency to tear or wear thin over time will inevitably increase maintenance costs and loss of business.
Agricultural operations also use composite geomembranes for a surprising variety of applications. Irrigation reservoirs, flowback storage ponds and anti-seepage irrigation systems are obvious candidates, Canals and troughs for flood irrigation as well as almost any other water collection and transportation activity on a farm is usually well-suited to RPE liners.
Questionable Alternatives
Whether you’re excavating a pond intended to house bass or crappie for relaxed weekend fishing, or one intended to hold your prized koi, your liner needs to be safe for both fish and aquatic plants. While this seems fairly obvious, there are a number of products chosen by DIY owners as cheap alternatives that can spell disaster for both fish and plants. Repurposed EPDM roofing liners and PVC pond liners are two important examples.
EPDM Roofing Liners
One common cheap alternative frequently sought out by backyard pond builders is repurposed EPDM roofing rubber. While it’s true that EPDM itself has long been recommended as a liner for small backyard ponds, the cheap roofing version you find could be manufactured from questionable materials like recycled tires, sawdust, and slate dust. Most alarming, recycled tires can bring in a host of toxic pollutants courtesy of their previous life.
Even “virgin” EPDM, designed for roofing applications, are frequently treated with a variety of chemicals intended to prevent anything from growing on it, including algae, bacteria and mold. These chemicals and coatings wreak havoc on the microscopic algae and colonies of beneficial bacteria that are so critical to maintaining a healthy environment in a fishpond. Some manufacturers use copper and zinc coatings instead, and these are directly toxic to your fish. Even if some fish survive in your fishing pond, you definitely won’t want to eat anything you catch!
It’s possible to find EPDM that’s been certified by the manufacturer as fish and plant safe, but it’s usually expensive. There are other important points to consider as well:
- EPDM is thick and heavy, and while it’s quite flexible to install in a generally rounded pond shape it’s difficult to install in tight corners where folds need to lay as flat as possible.
- The weight of EPDM makes it impractical for large installations since it must be shipped in relatively small pieces and then painstakingly glued together on-site with zero tolerance for leaks. In addition, the adhesive used for EPDM requires a dry surface. No matter the level of your enthusiasm, draining a pond is no fun.
- EPDM is particularly vulnerable to punctures; in a pond application, those can be a more common hazard than one would think. Since EPDM must be repaired with adhesive patches (similar to bicycle tires), mishaps during cleaning, the removal of large branches, and random encounters with sharp tools can require a laborious weekend dedicated to draining and repairs.
Flexible PVC Pond Liners
New pond owners may prefer to cut costs by choosing a cheap, widely marketed and easily available liner material like PVC (polyvinyl chloride), but the burning question is whether PVC is actually safe for fish and plants in the long run. Unfortunately, PVC on its own isn’t naturally very flexible, so manufacturers add plasticizers like phthalates to keep the material soft and flexible. Over time, those plasticizers leach out from the liner into the water, causing a twofold problem:
As the plasticizers are lost, the PVC naturally becomes stiff and brittle, making it substantially more vulnerable to cracks. Eventually, UV damage and loss of flexibility may become so significant that the plastic essentially crumbles at a touch. Regardless, once a PVC liner begins to develop cracks, it’s generally not worth repairing because the surrounding material around any repair is not likely to be strong enough to support it.
The second problem associated with leaching of plasticizers is more troubling. Phthalates are a type of endocrine-disrupting chemical and are known to be detrimental to the reproductive, neurological, and developmental systems of humans. There are also suspected links to heart disease, cancer, and early death in older populations. Phthalates are permanently banned in the use of some consumer products, and temporary bans are in place for others.
You may not plan on drinking the water from your fishpond or that lovely natural swimming pond, but over time, constant exposure to toxic materials will undoubtedly harm the health of most, if not all, creatures in your aquatic ecosystem.
