Installing A Do-It-Yourself Waterfall

Figure A

The side yard (figure A) already has a curving flagstone pathway and landscaping but needs a focal point. A corner area that slopes upward is perfect for the new waterfall.

Landscape designer John Kahlstrom recommends the pre-cast forms because they eliminate much of the digging and terracing typically involved in installing a traditional waterfall. He also demonstrates how to stain the concrete to give it a natural mottled look and surrounds the waterfall with boulders and a lush waterside garden.

Kahlstrom says that a professional would charge about $4,000 to build a waterfall in the traditional way using all natural boulders and stones, but do-it-yourselfers can buy the pre-cast concrete forms and other materials for about $850. This project is rated a 2 on a difficulty scale of 1 (easy) to 5 (difficult) and can be completed in two weekends with the help of friends for lifting the heavier stones.

Step One: Preparing the Site

For the greatest impact, a waterfall should be at eye level when you're sitting down. To accommodate the height of a waterfall, you need a slope and large enough area so that the waterfall is in scale with its surroundings. If you have a level area, you need to build up a mound at least 18 inches high, behind a flat area for the pond.

Rake out the area in front of the mound until it's smooth and level. Mark the outline of the pond area with landscapers' spray paint, giving it an irregular curving shape. Clear the rest of the site of any rocks, roots and other debris; mark where the waterfall will go.

Figure B

Build a simple retaining wall between the pond and base of the mound, using small boulders to help support the waterfall and define its shape. Choose 1-foot-long rocks with a rugged look and some flat surfaces to keep them stable and in place. Set the boulders upright, with the most attractive side facing out, to emphasize the drop from the waterfall into the pond (figure B). Fill in with soil behind the boulders to hold them in place. Smooth out and compact the soil so that it's level with the top of the retaining wall and so that the pre-cast forms will be stable.

Figure C

Step Two: Assembling the Forms

Pre-cast concrete forms (figure C) are durable and solid, come in a variety of styles and colors, and cost between $50 and $600 at garden centers. Most come in a kit with the plumbing, pump and tubing. The pre-cast forms have the right height for a waterfall, and the pieces fit together well and don't tend to leak like some pond liners.

Figure D

The natural structure of a waterfall is wider at the bottom and narrower at the top, so use a larger form as the lowest pool and place it on top of the retaining wall, slightly overhanging the wall and gently tilting forward. Place a smaller form on top of the larger form, making sure that it's balanced and that the spillway points into the larger form. Next, set the smallest form, the source of the waterfall, on top of the second form. The three forms (figure D) give the waterfall a height of about three feet, but you can use more or fewer forms depending on the look you want.

Figure E

Step Three: Placing the Pond

The pond is made of a fiberglass pond shell (figure E), 4 feet long in this case, available at garden centers for about $100. Dig out the pond area to fit the shape and depth of the shell so that the rim will be flush with the ground. Cover the floor with one inch of fill sand and smooth it out. Set the shell into the hole and make sure it fits snugly.

If you have loose soil near the pond, cover it with burlap, secured with landscaping pins, so that the soil won't slide into the pond. Fill the pond with water.

Feed 1-inch PVC tubing into the top form and attach one end to the plumbing. Attach the other end to a 550-gallon submersible pump to recirculate the water from the pond to the top of the waterfall. Place the pump into the pond and turn it on to test the water flow. Don't be concerned if the water looks dirty at first; the sediment will settle in a couple of days.

Figure F

Step Four: Completing the Waterfall

To hide the pond shell and give the pond a more rugged, natural look, line the bottom with cobblestones and cover any burlap with flat stones set on edge. Cover the rim of the shell with small, flat pieces of flagstone. Plant groundcover in the nooks and crannies between rocks to soften the edges (figure F). Add a few boulders along the sides of the pond and waterfall to hide the recirculating tube.

Once all the stonework is in place, you can apply concrete stain to the pre-cast form to make it blend in better with the natural stones. You can dab a little stain on the flagstones to make them blend in better, too. Kahlstrom applies three shades of concrete stain with sponge brushes.

Figure G

Starting with the dark shade and filling in with lighter shades, randomly dab stain on the forms to create a mottled effect (figure G). Let the stain dry for 1 hour and spray a light mist of water on the concrete and stones to help the colors blend together. Let dry overnight before turning on the waterfall.

Planting: A Waterside Setting

Choose plants that naturally grow alongside a creek or waterfall, such as grasses, sedges and ferns. Kahlstrom plants a coral bark Japanese maple tree for shade and texture and foundation plants around the waterfall to soften the edges. He also adds small blooming plants for a little color. His planting plan includes:

River wattle (Acacia cognata), Zones 9-11
Orange New Zealand sedge (Carex testacea), Zones 8-9
Corkscrew rush (Juncus effusus), Zones 6-9