Ponds can vary in shape from big, free-form bodies of water that you can swim or even fish in to formal reflecting pools. Prices run the gamut too, starting at less than $1,000 for a small lily pond to $25,000 and up for larger versions with fountains or waterfalls. The most common choices of homeowners are flexible-lined or premolded fiberglass ponds, both of which are relatively easy to install.
For a larger pond and a more naturalistic look, a flexible liner can take on whatever size and shape you want. Many are sold in kit form, complete with liner, pump, filters, and installation directions. To construct a liner pond, dig a hole by hand or backhoe, then back-fill with a cushioning layer of clay and sand, and top with a feltlike pond fabric to help protect the liner from punctures. Finish the sides with a surround of rocks or landscape plants.