An Overview of Pond Liners
When building a pond the first, and one of the most important decisions you will need to make is
choosing a pond liner. The three main types of pond liners are preformed shells, flexible liners and
concrete or concrete products. Each type of pond liner has its advantages and disadvantages, and care
should be taken to choose the liner that is best for you.
Preformed shells are pond liners that are molded into specific sizes, shapes and depths. Some shells
may also have a waterfall lip, stream, or a plant pocket or a shelf that is designed for water plants. (A
plant shelf should be at least 9 inches wide or it won't be usable.) The two materials used in preformed
shells are fiberglass and polyethylene (plastic); fiber glass is the material of choice. Although fiberglass is more expensive than polyethylene it is easily repaired, more resistant to ultraviolet light and if properly installed and maintained it will last up to 20 to 30 years. When shopping for a preformed shell the rule of thumb is: do some measuring at home before you leave for the store because they always look bigger in the store than when installed.
Flexible liners are the easiest to install, least expensive and most versatile of the three pond liners.
They are made of PVC (polyvinyl chloride) or synthetic rubber; either butyl rubber or EPMD (ethylene propylene diene monomers); EPMD's is the better product. EPMD is malleable and it is this flexibility that lends to it's popularity, because it will allow you an almost unlimited choice in pond designs. EPMD can be used in most water features and this versatility is the very reason EPMD is the liner of choice in streams, waterfall, pond and disappearing waterfall kits. EPMD is resistant to ultra violet light and because it is thicker than PVC it will also last longer. Flexible liners are susceptible to puncture, and some of the hazards to watch for are rocks, broken tree roots and gravel. Flexible liners should be cushioned with an underlayment or a pad. The best underlayment is a special underlayment pad that is tough, flexible, and designed for ponds. Sand, carpet padding and newspapers can also be used, but with mixed results. When shopping for a flexible pond liner make sure your liner is made for ponds, because some types of PVC and EPMD can contain chemicals that are toxic to fish and plants.
Concrete or concrete products (blocks) are another option for a pond liner; they are used primarily in
formal or raised ponds. A formal pond is characterized by clean geometric lines, either straight or
curved and neat regular borders. Concrete or concrete products will give you these crisp lines, square
corners, and uniform geometric shapes. However concrete or concrete products require a high level of
skill and knowledge to install , are expensive, and if not installed properly are prone to cracking and
leakage. Years ago concrete and concrete products were the pond liner of choice, but with the advent
of the new pond liners its popularity has wained.
The following is a quick summary of the advantages and disadvantages of the three pond liners.
Preformed Shells: 1) easy cleaning 2) long lasting 3) no design concerns 4) puncture resistant 5) small units can be easy and quick to install.
Flexible Liners: 1) least expensive of the three choices, 2) shapes and sizes are unlimited, 3) edges are easy to conceal, 4) easy to transport, 5) can be easily customized for marginal and wetland plants.
Concrete or concrete products: 1) good for a formal or raised pond, 2) if installed properly it can last a lifetime.
Preformed Shells: 1) edges are hard to conceal, 2) has to be perfectly level, 3) sizes and shapes are limited, 4) more costly than a flexible liner, 5) hard to customize for wetland and marginal plants, 6) to prevent buckling and warping a firm foundation and adequate backfill is required.
Flexible Liners: 1) requires an underlayment pad to help prevent punctures 3) less durable and will eventually degrades in sunlight, 4) exposed edges must be covered.
Concrete: 1) requires skill and knowledge to install, 2) installation is labor intensive, 3) can be prone to cracking and leakage, 4) most expensive of the three pond liners, 5) leaks are almost impossible to permanently repair.
Pond liners are the base for your pond, and care should be taken to choose the best pond liner.
Preformed shells, flexible liners, and concrete or concrete products are the three best pond lining
materials, and by weighing the advantages and disadvantages of each you will have a water feature that
will provide you with hours of relaxing enjoyment.