How to Connect Two Koi Ponds With a Waterfall

Call your local utility companies before you do anything else. Find out where underground pipes and electrical wires are, so that you can avoid digging into them.

Draw the waterfall path on the ground, connecting one pool to the other. Use spray paint to make the marks, it will be dug up later. Ideally, the waterfall should run from a higher to a lower elevation. This path can be a simple straight shot, or it can curve and meander like a natural stream. Digging it a little deeper in some places creates small natural pools. Digging sharp drops creates additional waterfalls.

Dig between the lines you painted to about a depth of 6 inches. Remove one of the stones that make the boundary of the lower pool, using the crowbar and hammer, so that the water can flow into it. Do not remove any stones from the upper pool or the stream will fill with water before you can finish working. Include at least one sharp drop for the waterfall.

Line the stream bed with an underlayment fabric. Place the pond liner on top of the underlayment. Use the shears to make the sheets the right size for your project. The liner and underlayment should extend about 2 feet past the edge of the stream.

Cover the bottom of the stream bed with flat rocks. Glue them in place with foam sealant. Use smaller rocks to fill the spaces between the bigger ones.

Place large rocks along the banks of the stream. Place the floating pump into the lower koi pond. Make sure that it is not touching the edges or the bottom. Run the return hose up alongside the large rocks to the upper pond. Partially cover the large rocks with a mixture of dirt and small rocks. Cover the hose and the edges of the pool liners this way, too.

Plant decorative plants along the stream banks. Drill a channel in the masonry between two stones from the upper koi pond just above the level of the water in the pond. The channel must be no wider than the pump hose, so that the water does not flow out faster than it is replaced.

Turn on the pump. The water in the upper pond will rise until it reaches the channel you drilled and pours out into the stream and returns to the lower pond. You may need to replenish the level in the lower pond a little.