The do-it-yourself (DIY) installation of a pond can be a fun and rewarding project, but it is important to understand that it will involve a considerable amount of time and effort.  Therefore, it is crucial to have a clear vision of the finished project prior to starting construction. Changing one's mind midway through may not be a practical option. Below is a step-by-step guide to creating an EPDM-lined, informal pond in your landscape.

Step 1: Mark your outline

Perhaps the simplest way to determine the exact shape of your future pond is to mark the outline by laying out a garden hose.  This will allow you to step back and take in the shape as it relates to its surroundings. A garden hose is easily re-positionable (a thick, cotton rope would also suffice) and can be repeatedly adjusted until the desired effect is achieved. Marking the outline with spray paint or pegs and string will quickly become a nuisance unless you hit upon the perfect shape on the first try. Remember, what you are marking now is the outline of the HOLE, not of the finished pond. Rock or other materials used to cope the edge of the pond will sit outside this line and can increase the finished size by as much as one third.

Step 2: Start digging

If the pond is to be populated with fish and plants, a minimum depth of 45 cm (18") is needed. The sides of the hole should be as shear as possible. This will result in any uncovered liner being less visible and will help to protect the fish and plants from visiting raccoons, etc. The bottom of the hole should be kept as flat as possible so that potted plants placed inside the pond will be stable. It is, however, a good idea to establish a very slight grade on the bottom to help with cleaning later on.

BUILDING SHALLOW PLANT LEDGES AROUND THE INSIDE EDGES OF THE POND IS RARELY A GOOD IDEA! Ledges facilitate fishing by raccoons. If marginal or bog plants are desired, it is a better policy to create a separate bog section outside the main pond. The bog is connected to the main pond only by a small channel and can be completely filled with plants. Other underwater plants can be moved up to the correct depth by placing their pots on bricks or rocks inside the pond.

Step 3: Prepare for liner

45 mil EPDM pond liner is extremely flexible and durable and should easily achieve a life span of 45 years or more if installed free from external dangers. Remember, the water in a pond is constantly exerting pressure on every part of the walls and floor, so rocks, roots, twigs, etc left touching the outside of the liner can eventually poke through. The solution is to provide padding behind the liner. Sand, thick felt, foam and old carpet are some of the many materials commonly used for this purpose, but no matter what is used, the underlying surface must first be smooth and free of protrusions.

Step 4: Place the liner

Drape the liner into the hole, centering it so the the excess is equally distributed on all sides. There should be at least 30 cm (1') extra on all sides - if not you will have problems later. Avoid the temptation to start trimming the excess now; this will be one of the final steps. Smooth the liner on the bottom and begin filling with water. With 10-15 cm (4-6") of water in the pond, the liner can be pulled tight on the sides and the major folds established. Pin the liner in place with rocks or bricks and pump out the water.

Step 5: Begin the coping

This is the most important stage. A quality professional pond builder is about 25% engineer and 75% artist. No matter what material is chosen for coping, take the time to make it right. Every rock will possess qualities which will determine its best location. Experiment until you find the right combination, being careful to consider every viewing angle. Most materials will look best with a level top face. Waterfall rocks should be as close to absolute level as possible. Check the relative height of the sides by running a 4' or 8' construction level or string level across the pond, or by using a laser. When every rock has found its place, they can be set with mortar or polyurethane waterfall foam if needed for stability. Remember to allow space for any incoming or outgoing piping as well as the pump's electrical cord. If possible, allow for an overflow drain to control the movement of overflow water during heavy rains. If mortar is used in locations where it will be exposed to pond water, it must be allowed to cure for 5-7 days before filling to reduce leaching of lime into the water.

Step 6: Complete the plumbing and electrical

Install whatever combination of pump, filter, overflow pipe, autofill valve, etc you've chosen. Use a union when connecting the pump to the piping for easy servicing later. Provide a GFCI (ground fault circuit interrupter) wet-location electrical outlet a minimum distance of 1 m (3') from the pond edge. Use of a proper GFCI protected outlet is extremely important when in the presence of water to avoid shock hazard.

Step 7: Fill the pond

Place the plants where you want them. Place any rocks destined for the bottom of the pond and set up hiding places for the fish. Fill the pond with water, adding a chlorine/chloramine neutralizer such as Oase's Water Prep Plus as the water is added. It is best to wait about a week for the water to settle before adding fish.

Step 8: Trim the liner

Now it is finally time to trim the excess liner. Pond liner can be surprisingly useful around the house and yard, so keep any larger pieces.

Step 9: Enjoy!

Step back and admire your handiwork (and don't forget to pat yourself on the back).