A pond must have a pond liner to function properly. The liner is what keeps the water in the pond so it will not seep into the earth, drying out your pond, and wasting a lot of water. The past saw an abundance of concrete liners poured in the fashion that swimming pools were. The problem with concrete is that is prone to cracking, especially during the freeze-thaw cycle. Since cracks mean the concrete needs to be replaced, everything must be uprooted and torn apart to fix the liner. Then you must go through replanting and re-stabilizing everything again. There are two basic types of pond liners, rigid and flexible liners.
Rigid Liners:
Rigid liners a pre-molded plastic tubs, similar to that of a bathtub. These liners are great for people just learning how to make and care for a pond, because they are easy to install and they are strong. Usually crafted from resin or fiberglass, they may also be simple black plastic, but either way they create a good strong liner for your pond.
These liners come in a variety of shapes, geometrical to more organic shapes. It could look really nice, if you have the space, to have a few different pools that flow into one another. No matter how you choose to place the pools, it will be easy to install and look good.
Flexible Liners:
Plastic polymers have created a revolution in the creation of pond liners. Buying a roll of EPDM or PVC now is an easy step, and can be laid into a hole as the ponds liner. These are more common now because they are safe for plants and aquatic life, and it features flexibility in temperatures ranging from -40 degrees Fahrenheit to 175 degrees Fahrenheit. These materials are also UV resistant so they will not become brittle with age, as many other plastics do.
The great thing about a flexible pond liner is it can be cut of shaped to meet any size or shape requirements. There are very few limits to your creativity! Short of a serious earthquake occurring, no shifts in the ground will cause this liner to tear and cause leakage. It is also pretty stretchy, so you won’t have to worry about tree roots growing under it!
It is a general practice to leave about two feet of the flexible liner around the edge of the pond, to account for unforeseen circumstances. This layer is easy to cover with dirt or edging materials. It is also a good idea to place an under layer to help prevent against any sharp rocks or objects!