Building a custom concrete rock pool waterfall takes a deal of time and energy, but is not beyond the skills of an average landscaping enthusiast. If you’ve poured yourself a sidewalk, built a simple bench or hooked up basic wiring or plumbing, you have all the experience you need to build your own custom, scratch-built backyard waterfall.
Mark off the area where you plan to build your rock waterfall. Drive 1/4-inch rebar rods into the ground about a foot apart. Follow the outline of your waterfall rock face. Cut off the tops of the rods at varying heights to create a rough outline for the rock face.
Bend 4-foot-long rebar rods into “U” shapes with the pipe wrenches or find something substantial to wedge one end into while you pull the other end over and around into a "U" shape. Drive the legs of the "U" shaped rebar into the ground to outline the edge of the receiving pool at the base of the waterfall rock face frame. The “U” shapes stick up out of the ground like a row of croquet hoops. Curve the edges irregularly, and vary the height of the “U” shapes.
Tie lengths of rebar cross-wise between the rebar uprights. Use pieces of varying lengths of rebar and bend them into irregular shapes to create bumps and dips to simulate rocks and boulders. When you are done you will have a frame of rebar squares forming the waterfall rock face and edge of the pool. Leave a 2 foot by 2 foot opening in the back of the waterfall for an access panel.
Tie roughly straight lengths of rebar across the bottom of the pool, staked with short pieces of rebar and tied at least 6 inches above the ground to allow room to run a drain underneath. Slope the rebar toward the back of the pool toward the drain hole at the base of the waterfall. Tie another row of bars perpendicular to the first row, making 1-foot squares on the bottom.
Cover the bottom of the pool with heavy plastic. Tie it to the frame and cover with chicken wire.
Tie chicken wire over the outside of the frame. Mold the chicken wire into rock-like shapes. Make sure you create a clear channel in the rock face to allow water to flow into the lower pool. Create a substantial pool shape in the top of the rock face for a feeder pool, into which the pump will push water to feed the waterfall. Cut a drain hole in the side of the catch pool so the water will drain when it reaches the depth you choose.
Cover the inside of the framework with heavy plastic. Tie it to the frame and chicken wire with light wire. Cut away around the access panel so you can get inside the frame.
Cut holes in the plastic and mount the spout assembly in the upper pool and the drain assembly in the lower pool. Both assemblies will feed down inside the framework.
Mix the cement mix according to instructions, no more than a wheelbarrow full at a time. Make the consistency thick enough to stick on the vertical surfaces of the chicken wire.
Trowel the concrete mix over the chicken wire frame. Don’t press too hard, just press the wire fully into the concrete coating and over the rebar underneath. Start at the bottom of the framework and work your way up.
Mix a bucket of thinset sand and aggregate concrete mix. Spread a thin layer of the wet thinset finish over the base concrete layer before it hardens. Add small rocks in various places and work them into the concrete layers while the materials are still wet. Don't overdo it. A light sprinkling of texture is all that you need.
Spray earth-tone concrete stain over the wet thinset, and work it in with the trowel to create rock-like shading effects. Cut thin irregular striations and cracks into the surface of the rock surfaces with the edge of the trowel. Also use the edge of the trowel to press lines around the edges of rock formations to define individual "rocks."
Wrinkle sheets of aluminum foil gently. Lay the foil flat over the surface and press the foil into the damp concrete. Allow it to set hard, remove the foil and move on to another section. Cut a hole in the chicken wire to set the drain assembly and “J” fitting in the bottom of the pool, the overflow drain assembly and the spout in the upper pool before covering the wire frame around the drains and water spout assembly with concrete.
Plumbing and Electrical
Attach a hose to the inlet of the water pump. Close the lid of the plastic tub and cut a hole in the top for the pump intake hose. Place the intake hose in the tub. Attach a hose to the pump outlet and its other end to the spout in the upper pool. Set the water pump inside the waterfall on the concrete pad.
Attach a straight pipe to the bottom drain and extend it out through the back of the rock structure. Cement the cutoff valve to the end of the drain pipe. Cut a hole for the overflow drain in the tub. Attach PVC pipe to the overflow drain assembly and run the overflow pipe into the plastic tub through the hole. The tub acts as the overflow water collector.
Dig a 2-foot-deep trench between the electrical supply and the back of the waterfall structure. Lay the power wire in the trench. Attach the wires to the pump following instructions that come with the pump. Attach the other end of the electric power wire to a separate circuit in the house breaker box.
Close the pool drain valve. Fill the pool and container with water. Turn on the pump at the breaker box. The pump will fill the upper pool and then spill over the face of the “rocks” to create a waterfall. As the pool fills, the overflow spills over through the overflow drain and flows back into the collector to be pumped back up to the upper pool.
Plant climbing plants and shrubs around the waterfall to give it a natural appearance.