image by 05-19-07 © Slobo Mitic/istock
Design a Landscape Waterfall
Select the location for your waterfall. To enjoy your landscape waterfall throughout the year, locate at least a portion of the stream where it's visible from inside the house. Sound is equally important, so locate the waterfall and stream where you can hear it from the house.
Decide on the dimensions of both the waterfall and stream: length, width, depth. The height of the waterfall's origin above the lowest point of the stream is referred to as "head." Along with the volume of water in your landscape waterfall system, head measurement and length of the stream from pump to waterfall will determine the strength of the pump you will need for your water feature.
Calculate how much water the pump will need to move. In a pondless waterfall system, this will require two calculations. To determine how much water will be in the stream, multiply the length by width by depth by 7.48 (gallons of water per cubic foot of space). The result will equal the gallons of water in the stream. The reservoir containing the pump will not hold as much water as a pond of equal size, due to the rock filling the reservoir. Assume the rock will take up 60 percent of the volume, and add .40 into the calculation. Reservoir gallons = length x width x depth x .4 (40 percent) x 7.48. Clearwater Landscapes recommends the reservoir should hold three times the volume of water in the stream for the system to function well. Adjust your measurements until this ratio is closer.
Purchase a water pump based on the gallons per hour (GPH) needed. Kits with all the required building materials are available, but you will still need to know the GPH requirement to buy the correct pump size. Pumps are rated with both a GPH flow and a maximum head height. You want a maximum head rating to be higher than the expected head elevation in your landscape waterfall; at maximum head, the flow will be zero. Water flow will be restricted by both head elevation and length of water travel from the pump to the top of the waterfall. Every 10 feet of hose length adds the same resistance as one foot of head elevation. Any sharp bends in the plumbing will also restrict flow. The width of your waterfall spillway will also determine the GPH rating. Every inch of spillway width equates to approximately 65 to 95 gallons per hour of water flow. Retail outlets that sell pumps will have conversion charts available to help determine the correct size pump for your design based on your calculations.
Purchase piping for your pump equal to the size of the outlet size on the pump. Mismatched pipe diameter -- for example, a one-fourth-inch pipe attached to a one-half-inch outlet -- will restrict water flow and reduce the lifespan of the pump. A larger diameter pipe and shorter pipe length will both increase the flow of your waterfall.
Build a Landscape Waterfall
Dig a hole for your submersible waterfall pump well to your design specifications. If the pump does not come with its own vault, you can use a milk crate or other sturdy, porous box to hold the rocks at a distance from the pump to ensure submersion of the water-cooled pump.
Line the hole and streambed with rubber pond liner material.
Install your pump per manufacturer's instructions.
Run the hose from the pump to the top of your waterfall. Attach to a weir (container), which you can either purchase or create at home, to the top of the hose, where the water will gather at the top of the waterfall before spilling over the lip of the spillway. Use non-toxic silicone sealant on the hose connections and secure with hose clamps.
Bury the exposed length of hose or otherwise conceal from view.
Fill the well around the pump vault with rock and decorate the streambed.
Fill with water and run your landscape waterfall.