Building a pond or water feature

Labor intensive but not hard, building a pond is fun

Backyard ponds

If you’ve done all the research and planning, building your dream water garden, pond, or waterfall isn’t going to be all that difficult. Once you decide what kind of water feature you want, where it’s going to go, how big and deep it’ll be, and the types of plants and fish you want, putting in it is mostly about perspiration. Now it’s time to get your hands dirty!

Liner or rigid shell?

Though there are other ways to create a small pond or water feature, most homeowners opt for either a simple "instant" pool using a rigid preformed liner or the more ambitious pond using a flexible EPDM liner.

The first choice of many homeowners is the flexible liner, which comes in various grades: PVC (polyvinyl chloride), EPDM (ethelyne propylene diene monomer), and butyl rubber. The least expensive is the PVC, which we don't like and won't recommend simply because of its unsustainability and toxic nature. Butyl rubber is expensive and difficult to find in the U.S. Though widely used in Europe, it is regarded by experts as an excellent choice because of its flexibility, strength, and longevity. EPDM is durable, flexible, and affordable. A 45-mil thickness is fine for most small residential ponds or pools.

Rigid liners are much easier to install, suitable for smaller yards or gardens, and relatively low cost. A motivated homeowner could easily purchase all the materials and install it in a weekend. Small ponds like these also lend themselves to solar-powered fountains, which can give you the advantage of a full-fledged water feature in a tiny space. The downside of a rigid liner is, of course, the limited number of choices you have with respect to size and shape. Rigid shells lend themselves to raised pools often needing only a reasonable enclosure to make them stable. Made of fiberglass, they may not be the most attractive, though they are easily camouflaged, but they are sturdy and generally trouble free.

Laying it out and calculating the amount of liner

Use a hose or rope (flour and spray paint also work) to lay out the shape you want your pond to be. Measure the maximum length and width of the pond—stretch the measuring tape across the widest section of the pond, then across the longest section—to obtain the rectangular measurement of your pond.

Next, calculate how much liner you’re going to need. A good formula for doing this is to take the maximum depth of the pool (usually about 2 feet) double it, and add the total to the width and length of the rectangle. To make a foot’s worth of overlap, add an extra 2 feet to the width and length of the liner.

In other words, if you have a pond that is 10'x12' at its maximum width and length with a depth of 2', then the calculation would look something like this:

Length (12') + depth doubled (2' x 2' = 4') + additional overlap for liner (2') = 18' total length
Width (10') + depth doubled (4') + additional overlap (2') = 16' total width

Thus, you’ll need a 16'x18’ liner for this pond, even though the length and width are only 10'x12'.

Dig it!

So now that you’ve got the liner all figured out, it’s time to start digging and leveling the pond. The first set of instructions is for installing a flexible liner; the second set is for installing a preformed shell.

To install a flexible liner

Step 1: Remove the turf.

Using a flat shovel, remove the uppermost layer of grass or sod within the pond area. Don’t forget to also remove grass about a foot around the perimeter to make a flat surface for your edging.

Step 2: Get your hands dirty!

You have two options when you come to this part of the project: You can either dig a dirt shelf around the perimeter of the pond that is up to one foot deep and one or more feet wide, or you can opt to use 2x8s or 2x4s and bricks for stands instead. Keep in mind that dirt shelves deteriorate over time and also limit where you can put your plants. The advantage to using bricks is that you can move them around whenever you want to, your fish will have a place to hide, and you’ll get more water volume.

If you do choose to use dirt shelves, create the first and shallowest shelf for marginal plants—plants that like shallow water—by digging along the edging to a depth of eight to twelve inches. Mark the outline of the first shelf with sand or rope. Take out all the dirt within the pond by layers, beginning in the center and moving outwards. To allow for the sand layer on the bottom, you’re going to need to dig an extra two inches deeper than the pond depth. Create more shelves during this process or dig until the required maximum depth has been reached.

Include a deeper section if the pond is likely to freeze during the winter or get too hot for fish during the summer so they will have a place to go. This area should be about three feet deep and three feet wide. If you’re just going to have plants, this isn’t necessary. If you’re including a waterfall, dig the remainder of the pond with a slight slope to the end opposite the waterfall.

Check that your shelves are level using a carpenter’s level. Place the level on a long straight board placed over the hole and respective shelves. Also, check the hole for sharp rocks or roots and take them out.

Step 3: Install the filter and/or skimmer.

If you’re going to have fish in your pond, install a filter and skimmer to keep the water safe for them, since fish waste eventually kills them. Install these before putting in the liner, following the manufacturer’s instructions. Making your own filter is a lot cheaper than buying one, (especially if your pond isn’t that large) and instructions on how to do this can be found in many ponding catalogs and instructional books.

Step 4: Lay the underlayment and liner, then fill the pond

Add an underlayment to the bottoms and sides of the pond. You can use old carpet, carpet padding, or even an inch thickness of newspapers. Or purchase pool underlayment designed specifically for ponds and pools. Both will prevent an overlooked sharp rock or root from puncturing your liner.

Drape the liner into the hole, making sure the overlap is even on all sides. Once you’ve gotten the liner into position, smooth out any kinks as best you can, then weigh down the edges with several smooth flat stones or bricks. Turn on the hose and begin filling the pond. As the water rises, make sure to fold and tuck the liner into corners, and remove the stone weights off the edges to avoid stretching it out too much. When the pond is full, cut off the excess lining, but leave enough liner around the rim of the pond so the edge rocks will have something to sit on.

Step 5: Set the edging and populate the pond.

Drive stakes or 20d nails through the liner into the ground every foot or so to keep the liner from slipping when you add the edging rocks. Now you’re free to try out different designs of the rocks you’re using to see which look best. Once you’ve found the winning arrangement, mortar the stones in place to prevent moving or slipping into the pond. You want the stones to hang over the pond just half an inch or so to hide the liner, but not so far that they might fall in.

Add the fish and plants you’ve chosen for your pond, and you’re all set to enjoy a beautiful water feature for a long time to come.

To install a preformed shell

Step 1: Plot the shell outline.

This requires at least two people. Flip the preformed shell upright in the location you’ve chosen for the pond. Plot the outline of the pond using stakes if the pond is asymmetrical or something noticeable like flour or a garden hose if it’s completely symmetrical. Remove the turf as in step one.

Step 2: Dig yourself into a hole.

Dig a hole in the shape of your preformed pond shell, adding an extra two inches around the perimeter of the pond and two or three extra inches in the bottom of the hole. If the preformed pond has shelves, you’re going to need to cut ledges in the appropriate areas to support the shelves. Don’t just leave this part out! Measure the preformed shell carefully to get calculations on the width of the shelves and how high up they will be. If you don’t cut ledges for these parts, the shelves will begin to sag and it will be hard to put plants on them to say nothing of breaking. As with the flexible liner, it’s also with the preformed liner to remove any rocks or sharp objects from the hole before laying the liner or sand. Line the bottom with two or three inches of damp sand (builder’s sand, instead of play sand, is the best for this type of job, same goes for the flexible liner).

Step 3: Test shell fit, tweak until correct and level.

Use a carpenter's level to make sure the bottom of the pool is flat. Don't forget to dig to accommodate the two inches of sand which will create the bed under the shell. This might be a trial-and-error process; you might have to take the shell out if it’s not the desired height or if it doesn’t fit properly. Also, as with the flexible liner, use a level placed across the rim of the pond to check and make sure it’s not lopsided.

Step 4: Set the shell.

Place the shell into the hole. The final height of the rim should be about 1 inch above the ground to prevent runoff from rain entering and polluting the pond.

Step 5: Fill the pond, backfill the hole surrounding the shell.

As the water is filling the pond, backfill the hole around the shell with dirt or the extra damp sand you used for the bottom of the hole. Pack the dirt or sand firmly into place around the liner making absolutely sure to pay attention to details like small nooks and crannies.

Step 6: Add edging, fish and plants.

After the pond is full, conceal the exposed preformed shell rim with rocks or overhanging plants. Use wide flat rocks like flagstone to overhang by at least an inch or a little more to conceal the liner. Finally, add your fish and plants, and you’ve got yourself a beautiful and functional water feature.

Resources

Garden Pools, Fountains, & Waterfalls by Scott Atkinson and the Editors of Sunset Books.


More money than time? If you want to add a water feature to your yard or garden and need a pro to help, a qualified pro is easy to find through ContactorNexus .

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