How To Create A Backyard Pond

Dan’s pond attracts birds, frogs, butterflies, and crickets (no mosquitoes, though, thanks to the moving water). It also attracts Dan and Gloria. The couple often sip their coffees there while watching the sunrise, and lounge by the gurgling water after dark. “My wife is actually really glad I did this,” says Dan. “And so am I—it’s so relaxing.” Now, we figure if a retired schoolteacher can build a pond in a weekend, so can you. So we asked This Old House senior technical editor Mark Powers to show you how to make the one you see here—just like Dan’s. All you need is a shovel and a few materials, and before you know it, you’ll have your own little “great lake” to enjoy.

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Creating a Backyard Pond: An Overview

A free-form pond like Dan Gibbon’s can be customized for any landscape, with different rocks, plants, shapes, and waterfalls. But we’ll give you some helpful points on placement, size, and materials.

Where to build your pond

Before you start, call 811 or your local one-call center to have electric and gas lines marked so you know where to dig to steer clear of them. Then, when you map out the location of your pond, put it where it will be noticed—visible from a window, off a patio, or along a walkway—but away from the play areas of small children or pets. Keep clear of major root systems or mature trees, which can block too much of the sunlight plants and fish need. You’ll also need to be within reach of a grounded exterior outlet so you can plug in a pump, an essential tool for keeping the water aerated; most pumps come with a maximum cord length of 25 feet, and extension cords are not recommended. You may need to bury the power cord a few inches down in PVC pipe to hide it. Space permitting, you need at least 40 cubic feet for your pond—about 7 feet by 4 feet—to keep the water clean. An initial shallow terrace just inside the perimeter of the pond holds rocks that conceal the liner edge and keep it in place. A second, deeper terrace supports plants that live in the water and help balance the pond’s ecosystem. As you dig, you must slope the sides of the pond so that if the water freezes, the ice will push up instead of against the liner. Even in warmer climates, small ponds can change temperature rapidly, so if you’re adding fish you’ll want a deeper pond that will maintain a more consistent temperature and accommodate the fish—18 to 24 inches for goldfish and at least 3 feet for koi.

Additional materials

To maintain the consistent depth of the water, you need to line the pond. A thin layer of sand and old newspapers or burlap bags softens the jagged edges of rocks and roots. But over that, you will need to put a waterproof skin. There are several types of flexible liners meant for small ponds—made from polypropylene and EPDM, among other materials. Look for one that’s weather-resistant, so it will stand up to UV rays and freezing temperatures. It should also be rated “fish-safe” if you plan to stock your pond and come with a warranty of 10 to 20 years so your pond will be watertight for many years to come.

How to Build a Backyard Pond: A Step-by-Step Guide

Step 1: Excavate the area

Layout the size and shape of your pond with a rope or garden hose. Using a spade, dig down 3 inches in a 1-foot-wide ring outside the outline to create the stone-border shelf. Next, create a plant terrace by digging a 1-foot-wide shelf 8 inches deep inside the rope outline. Only dig the terrace in areas where you plan to put plants. Continue digging inside the plant terrace to make the bed of the pond—a minimum of 18 inches deep, with a slight slope.

Step 2: Level the pond’s edges

Set a 2x4 across the excavated hole and lay a level on top of it. Roughly level the pond’s edges. Then carve out a 6-inch-wide, 1-inch-deep channel on one side to redirect overflow. Also dig a shallow trench to the nearest electrical outlet for the PVC conduit, which will hold the pump cord.

Step 3: Prepare the base

Beginning in the center of the hole, distribute a 1-inch layer of sand around the entire base and on the terraced shelves. Cover the sand and the sides of the hole with a ½-inch-thick lining of newspaper to provide a protective layer under the lining. Smooth the entire surface by hand and remove any roots or stones that could bulge through the lining.

Step 4: Line the pond

Cut a piece of liner to be 4 or more feet wider and longer than the pond. Center the liner over the hole so there are 1 to 2 feet of excess on one side and the rest of the excess is on the opposite side. Set two stones on the shorter excess to hold the liner in place. Beginning at this end, press the liner down along the inside edge and then along the bottom of the hole, working your way around the pond. Smooth out creases and folds and push the liner tightly into crevices.

Reader Tip: “Avoid building your pond directly under a tree or you’ll find yourself cleaning quite a few soggy leaves in the fall.” —Dave Martin, Natick, MA

Step 5: Fill the pond

Using a garden hose, fill the pond with water. As it fills, continuously pull the liner taut on each side. If necessary, have a helper pull from the opposite direction. Fill the pond until the water reaches the top border shelf.

Reader Tip: “Whenever you water your plant beds, also ‘water’ your pond to make up for any liquid that has evaporated over the week.” —Dan Gibbon, Medford, WI

Step 6: Install the pump

Thread the pump’s cord through a section of PVC conduit cut to length. Place the PVC conduit in the trench and backfill the soil. Hold one end of the recirculating hose as you set the pump in the deepest part of the hole.

Step 7: Create a rock border

Fill the overflow channel with pea gravel for drainage. Arrange flat rocks along the border so the liner’s edge is covered but no more than one-third of each rock hangs over the water. Then, cover this first ring of rocks with a second one. Stagger the seams between the stones, and set them back from the edge of the first ring a bit. Arrange and rearrange the rocks until they sit in an interlocking position. Experiment with your outcropping until you have a natural, staggered look.

Step 8: Secure and conceal the hose

Where the hose exits the water, wedge it between two rocks without crushing it. Conceal it with a third rock. Arrange and secure the hose through the rocks and over a stack to position the waterfall. Once the pump and hose are secure, plug the cord into an exterior GFCI outlet. Watch the water flow and make sure it looks natural leaving the hose but still spills back into the pond.