Pick a spot for your cascading waterfall. Make sure that you call your local utility company before you begin digging to ensure that you will be building your waterfall in an area that is free of any underground wires.
Outline the shape of the reservoir for your waterfall. The reservoir can be any size, but for this particular cascading waterfall, the size will be approximately 3 feet wide and 3 feet long. The size of the reservoir will determine how much water will be circulated to the waterfall. In "Resources" you will find a water-volume calculator.
Excavate the waterfall reservoir, using a shovel. Creating a reservoir that is 3 feet deep, 3 feet long and 3 feet wide will allow roughly 200 gallons of water to circulate through the waterfall, allowing a decent amount of water to cascade down the rocks. So, the depth of this reservoir should be 3 feet.
Place the pond liner into the waterfall reservoir and pull the sides of the liner over the edges of the reservoir. Secure the liner with landscaping rocks.
Place the pond filter onto the floor of the reservoir and attach one water line to it.
Pick a spot around the reservoir for your waterfall. The location doesn't necessarily need to be on higher ground because the rocks will provide the illusion that the waterfall is at a higher elevation.
Remove the top layer of soil where you will be building the cascading waterfall. The waterfall needs to begin directly at one of the edges of the reservoir. To provide enough room for the rocks, the size of the waterfall should be at least 1 foot wide and 3 or 4 feet long. However, the size of your waterfall is completely up to you.
Place the pond pump in the waterfall section, close to the reservoir. Connect the other end of the water line to the pump. After you have done this, connect the second water line to the pump and lay it down horizontally in the waterfall section.
Add landscaping rocks to the waterfall section, providing the cascading effect. Place the landscaping rocks into the section, overlapping them to create the elevated ground illusion. Cover the entire waterfall section with these rocks. Discreetly hide the pond pump and water line so that the cascading waterfall will have a more natural appearance. Do not crush the water line with the rocks; just position the water line up the rocks.
Fill the waterfall reservoir with water to its brim.
Turn on the pond filter and prime the pond pump. Refer to the owner's manual of your pond pump before priming, as every model works differently. Enjoy your new cascading waterfall.