Pools can be built out of either earth materials, flexible liners, fiberglass or rigid plastic, or concrete. Each of these materials offers certain advantages and disadvantages. Earthen ponds are inexpensive, especially for larger pools, but can have seepage problems if built in the wrong soil, and wild plants will be more likely to establish. Flexible liner pools are easy to construct and are fairly inexpensive but punctures are possible and they must be pumped or siphoned to drain. Fiberglass or rigid plastic liners are durable, offer long life and can act as plant-only pools.
Rigid liners are generally shallow and can crack in extreme freezes.
A concrete pool can be very expensive but will have an extremely long life. It can, however, have problems with cracking later in life. When constructing ponds, consult your local building and zoning agencies so that you can comply with any building codes and permit requirements that may be needed. When constructing any ornamental pools, it is best to have to have a good plan before initiating any construction. Outline the area in which you are working.