An above-ground pond can be constructed if the location where you would like to place a pond is restricted by hard soils or tree roots. One method of pond construction involves the use of concrete blocks, which are stacked along a foundation and covered with a pond liner. Construction of the pond can be completed in an afternoon with supplies that are purchased at your local hardware store or garden centre.
Place a stake at the centre point of the area where you would like to place the pond. Cut a string to the length of the desired pond diameter and tie the string to the bottom of the stake. Pull the string horizontally from the stake and use the string as a guide to mark a circular pattern for your pond layout. Use a piece of rope to mark the outline of the pond.
Use a spade to remove grass from the pond area, then excavate a 3-inch deep trench along the perimeter of the pond. Matching the width of this excavation to the width of the concrete blocks you will use to create the walls of the pond.
Prepare the pond foundation pad by placing 4 inches of crushed rock in the perimeter trench. Lay a piece of lumber across the top of the pond area and use a level to create an even surface, adding rock as necessary.
Create the first course of the pond wall by laying the concrete blocks end-to-end in a circle along the foundation. Stack two additional courses and check the blocks for level placement at each course.
Place a piece of pond liner across the ring of blocks. Push the liner down so that it is flush against the pond wall and fully covering the bottom of the pond. Cut the liner, leaving a 6-inch overlap that is placed on top of the third course of blocks. Add a fourth layer of blocking to secure the liner, using a concrete adhesive along the sides of the blocks to lock the concrete together and prevent unwanted separation.
Use a garden house to fill the pond with water, then add any desired water plants or pond decor.