A Step-by-Step Guide to Lining a Pond


For the seasoned water gardener, liner ponds are the way to go because of their flexibility during construction. However, liner ponds also need advanced preparation for the same reasons. The first step in building a pond with a liner is getting one that fits your pond’s measurements. Using a pond liner calculator (like the one found on would be best to calculate the correct liner size. Here we’ll go over the steps you need to do to build your own liner pond.

EPDM (Ethylene Propylene Diene Monomer) liners of at least 45 mils thick are suggested. EPDM is a durable substance that maintains flexibility from freezing to boiling, or -40 to 175 degrees Fahrenheit. Since it lacks the plasticizers found in most lining materials, it won’t dry out and crack with time. EPDM is resistant to the deteriorating effects of ultraviolet radiation (UV), and its high expansion and contraction qualities allow it to conform to rocks and tree roots in the earth’s subgrade, extending its lifespan relative to other liner materials.

Start by laying out the pond’s perimeter with rope or a garden hose after you’ve planned it on paper and acquired all the necessary items. The first step is to dig a coping shelf around the pond’s edge. The coping shelf will keep the boulder, rockwork, and liner overlay in place. The ideal dimensions for the coping frame are 16–18 inches in width and 2 inches in depth. When excavating the coping shelf, a square shovel is preferable to a round or sharp-pointed one because it will not leave behind furrows.

Dig a bog shelf for plants once you have ensured the coping frame is even around the pond. Shelves typically sit 9 to 12 inches below the water’s surface in ponds. After that, you need to excavate the deepest part of the pond. The ideal angle of the deep area’s slope from vertical is 20 degrees.

Sharp stones or roots should be removed from the hole before installing the liner. You can now line the excavation with pond underlayment if you so choose. Underlayment is not required but is recommended to protect the liner from below. Smaller pieces of liner underlayment can be overlapped without issue. Smaller underlayment pieces may shift once the liner is installed, so taping them together is a good idea.

The liner must be put into the hole with great care. Although a 45 mil liner is thick and sturdy, it is still essential to take precautions to avoid tearing or puncturing it during installation. In contrast to the underlayment, the liner must be installed as a continuous sheet. Folds in the lining can act as a trap for dust and filth, so try to avoid them as much as possible. A liner in pristine condition should survive for 40 years at the very least before showing signs of wear.

You can begin filling the pond with water at this point. Stop the hose occasionally while you fill the pond to eliminate any creases in the liner. After the pond has been filled, any surplus liner can be trimmed down, but it should be long enough to go over the coping ledge and beneath the proposed edging. Boulders or long nails can be used to secure the liner. Applying edging materials around the liner will help keep it in place and give your pond a more natural appearance.

The hardest part of the setup is over at this point. The final steps are to put in place the pump and embellish the pond area. If you have an overwhelming desire to increase the size of your water garden, a cascade or waterfall is an excellent addition to consider making.

Please visit for additional details about liner pond installations. offers liner pond kits that include the liner, pump, and fountain heads needed to build a pond.

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