How to Place a Liner Under the Waterfall

Install the pond, pump and waterfall box according to the manufacturer's instructions.

Dig the path of the waterfall using a shovel. Remove all roots and rocks from the spillway and waterfall. The depth of the spillway includes 2 inches of sand, the rocks installed over the liner and 1/2 to 2 inches of flowing water.

Place a board across the spillway and set a spirit level on it. The sides must be horizontal; otherwise the water may flow over the edges instead of down the waterfall.

Change the angle of the board to follow the course of the spillway. Use the spirit level to ensure the spillway slopes downhill.

Rake 2 inches of sand down the spillway. The liner needs a smooth surface to prevent tears and wrinkles.

Arrange the large, flat spillway and waterfall rocks according to your plan. Once the rocks are arranged to your satisfaction, move them to the side.

Unfold the liner, and lay it across the waterfall and spillway. The liner should extend all the way to the bottom of the pond, on top of the pond liner or shell. Place rocks on the liner's bottom and sides to hold them in place.

Tug the liner up and to the sides to remove wrinkles. If the liner doesn't cover the length of the spillway, place a second liner on the upper section of the spillway and over the berm. The upper liner should overlap the bottom liner by at least 2 feet.

Attach the upper section of the liner to the waterfall box according to the manufacturer's directions. Attach the upper and lower liners with silicone sealant or liner seam tape.

Put the large, flat rocks back into place on the spillway and waterfall, working from the bottom up to the waterfall box. Settle each rock securely in place before adding the next rock. Arrange smaller river rocks along the sides and around the large rocks.

Fill the pond with water. Turn the pump on and check the entire installation for leaks. Add or adjust the small rocks to change the path of the water in the spillway and over the large rocks.