How to Install a Liner Pond

Liner ponds are ideal for the experienced water gardener because they allow for very forgiving installations, which consequently promotes greater creativity. However, for the very same reasons, liner ponds also take require some pre-planning. Before you commence a liner pond project, you should purchase a pond liner that is of the appropriate size for your pond dimensions. To determine the appropriate liner size, it is recommended that you use a pond liner calculator (I.e. like the one on’s website). To follow are instructions and tips on how you can install your very own liner pond.

It is recommended that you purchase an EPDM (Ethylene Propylene Diene Monomer) liner that is at least 45 mil in thickness. EPDM is a highly stable material that stays flexible in temperatures from -40 degrees Fahrenheit to 175 degrees Fahrenheit. Unlike other liner materials, it does not contain plasticizers that could cause it to become brittle with age. EPDM will also last longer than other liner materials because it is resistant to the harmful effects of ultraviolet radiation (UV), and it has high expansion and contraction characteristics that enable it to conform to rocks and tree roots in the earth sub grade.

Once you have designed the pond on paper, and purchased all the necessary materials, you should start by marking the outline of the pond with rope or a garden hose. Start by digging a coping shelf around the perimeter of the pond. The coping shelf will help to hold the boulder, rockwork, and the liner overlay into place. The coping shelf should be approximately 2″ deep and 16 to 18 inches wide. It is recommended that you utilize a square shovel to dig the coping shelf, because round or sharp-pointer shovels can leave small furrows in the dirt.

After ensuring that the coping shelf is level all around the pond, dig a bog shelf for plants. Most ponds are designed with shelves 9″ to 12″ below the water level. Afterwards, the center (I.e. deepest area) of the pond should be dug. The deep area should slope in approximately 20 degrees from the vertical.

Prepare the hole for the liner by removing sharp stones or roots. At this point, you have the option of lining the excavation with pond underlayment. Although it is not mandatory, underlayment helps to cover the entire surface, to protect the liner from below. Liner underlayment does not need to be in a single piece, hence smaller pieces can be overlapped. However, it is recommended that you tape smaller underlayment pieces together, to keep the pieces from moving after the liner is placed on top.

The liner should be carefully laid-out into the hole. Although a 45 mil liner is thick and durable, care must be taken to make certain that the liner is not damaged or punctured during installation. Unlike the underlayment, the liner must be a single unbroken sheet. Try to minimize the folding and pleating of the liner, because folds have the potential to trap dirt and debris. A perfectly intact liner should last for 40 years before it begins to deteriorate.

Now you’re ready to fill the pond with water! As you’re filling the pond, stop the hose periodically to smooth out wrinkles in the liner. After the pond has been filled, you can cut off any excess liner, but make sure that enough material is left to allow the liner to extend over the coping shelf (and underneath whatever edging is planned). The liner can be anchored with boulders, or long nails around its edge. Edging materials should be applied around the liner to weigh it down, which has the added benefit of giving your pond a natural look.

At this point, the most difficult part of the installation has been completed. All that remains to be done is to install the pump, and decorate around the pond. However, if you find yourself with an uncontrollable urge to expand your water garden, you should definitely consider the installation of a cascade or waterfall.