Outline the shape of your pond with a shovel, adding an extra 1′ in all dimensions. Be sure to slope the side of your pond to add stability; after all soil is removed check carefully that the top edges of the pond are level – they must be level before you begin to install the pond liner.
Line the bottom of the hole with pond liner underlay. This protects the pond liner from damage.
You can now begin putting the pond liner in place, first by draping it loosely over the excavated area. You may wish to gently pat the pond liner to conform to the shape of your excavated area. Place a few stones or bricks around the top perimeter of the pond liner to loosely hold it into place.
Slowly begin filling the pond. The weight of the water will gradually allow the pond liner to assume the shape of your excavated hole. As you fill, the pond liner will likely shift and you will need to make adjustments in the stone weights to assure that the pond liner fits snugly to the contour of the sides and bottom. Continue to fill to the desired level.
Now, your personal creativity can take over! You may edge the pond using decorative flagstone, plants, brick, or a medium of your choice. To hide the edge of your pond liner, overlap whichever edging you choose to form a narrow “lip” over the pond. If, in the process of completing your project, the water becomes muddy, drain the pond and replace with clean water. Never allow dirty water to remain in your pond, as this will lead to odors and may be toxic to fish and plant life within your pond.