The simplest waterfall to build begins with a natural slope beside an existing garden patio. The slope, in fact, is all but essential; if your yard does not contain a pond, you can install a fiberglass pool. In most other respects, the size and shape of the waterfall are limited only by your imagination. Study natural waterfalls for ideas. Consider, too, the points from which you want to view the waterfall. Then mark outlines for the trough and discharge pool on the ground with powdered chalk.

With the pool in place and the waterfall plan marked out on the ground, determine the size of pump you will need. A backyard waterfall should circulate between 100 and 400 gallons of water an hour. Measure the total height of the fall-the vertical distance from the bottom of the pool to the top of the trough-and order a pump that will lift 100 to 400 gallons per hour to that height.

The shells of the trough and discharge pool consist of premixed concrete troweled onto beds of gravel and reinforced with steel mesh. An 80-pound bag of concrete will make 1/2 cubic foot, enough to cover about 1-1/2 square feet when spread four inches thick. To determine the areas of the shells, measure the trough and the discharge pool separately, then add 10 per cent to allow for the extra area created by the pool’s depth.

Both of the concrete shells are painted with a thin layer of masonry bonding agent, and then coated with a one-inch-thick layer of black waterproof mortar; the mortar not only makes the surfaces leak proof, but serves as a bed for the decorative stones. You will need enough mortar to cover the entire surface of the trough and pool, and an additional quantity to bond the stones in place. One cubic foot of mortar spread an inch thick covers 12 square feet.

Mix the concrete and the mortar separately in a mortar pan, stirring with a shovel. To mix the concrete, pour a bag of premixed concrete into the pan and add just enough water so that a handful will barely hold together in a clump. To make a cubic foot of mortar, mix 100 pounds of fine builder’s sand with 16 pounds of Portland cement and 18 ounces of black cement pigment (sometimes called carbon black), then add enough water to make a stiff mixture that will stick to a trowel held upside down.

Stone for the fall itself and for the camouflage of the concrete shell can be harvested anywhere you find it – wondering down the beach shore, walking along streams, even along sides of fields where farmers commonly throw stones that could wreck their equipment. Or you may purchase it from a quarry; many quarries will also deliver the stone to the site, but you can cut costs by transporting it yourself. Handle all stone carefully to prevent nicks and breaks that can spoil the weathered appearance.

Premixed concrete, Portland cement, cement pigment, wire reinforcing mesh, masonry bonding agent, gravel and builder’s sand are all available from masonry suppliers. You will need a few specialized tools: a mason’s trowel, a float and a tuck pointer. If you must cut stones to fit, you will also need a mason’s chisel and the short-handled mallet called a maul. Always wear heavy gloves and steel-toed work boots when  working with concrete, mortar or stone and, if you cut stones, wear safety goggles.