Like ponds and water gardens, waterfalls add a sense of beauty and calm to your home landscape. For those who love the sound of water cascading off rocks or spilling into a pond below, a waterfall is the perfect addition to the yard. If you’ve recently installed a pond or a water garden, you might be considering including a waterfall to aerate the water and create a melodious sound. This project is often not a hard one, especially if you use a “weir” or a plastic box to create the waterfall. Even building a natural waterfall is relatively simple if you spend a little time planning and designing beforehand.
There are a few considerations to make before starting on the design process for your new waterfall. Here are a few things to think about before you begin:
Often, many first-time builders make their ponds too small and their waterfalls too large. The waterfall should compliment your pond or yard, not overwhelm it. For example, a pond measuring 12’x14’ should have a waterfall drop no higher than 18 to 24 inches. (Note: The volume your pond has to be large enough that when you turn the waterfall off, the water won't overflow the pond.) It’s important to consider the scale of your yard, house, and pond when deciding on the width and height of your waterfall. Look at pictures of different styles of waterfalls in books, magazines, or on the internet. Seeing the way the water flows around and over the rocks will help you make a decision on what style you like best.
You also have to choose whether you’re going to use a weir or if you’re going to make a “natural” waterfall using soil and rocks. A weir is a plastic box with one side that’s lower than the others, so when the pump fills the box with water, it spills out over that one side back into the pond. With both the natural and weir constructions, you’ll need to either excavate a series of levels leading to your pond if you have a natural slope, or create a slope using soil and install the weir or rocks in that. With a weir, after you install it in your slope, you can just run tubing from the pump into the weir. Pretty simple, right? If you don’t like the idea of looking at a plastic box waterfall, you can camouflage the plastic by placing rocks around it and putting in some hyacinths or other floating plants.
If you’re going with a natural waterfall, you’ll follow the same process for the first part of construction: create the slope. However, during the second part you’ll need to actually figure out the kind of rocks you want, how to position them, and where the pump and filter are going to go.
Once you’ve decided which kind of waterfall you’d like and where it’s going to go, think about the sound it’s going to make. Waterfalls should have at least 100 gallons of water per hour flowing per inch of width. That means that if you have a 15 inch waterfall, you will need to have approximately 1500 gallons flowing over it per hour to have it look its best. The amount of gallons per inch you want to pump through the waterfall also depends on how much noise you’d like the waterfall to make. If you want something a little louder, you could pump 150 or more gallons per inch, whereas if you want something a little more subtle, you could reduce it to as little as 50 gallons per inch.
The other factor in creating the optimum sound for your waterfall is how far the water is falling and what it’s falling on to. You can experiment with the sounds different heights make by using a garden hose and a large bucket and adjusting the distance between the two. If you are planning on having the waterfall flow onto rocks, you may hold the garden hose a little bit above a few rocks in the garden to see what it might sound like. It won’t be exactly the same, but you should be able to get a general idea of the volume and texture of the sound from doing this.
Once you’ve figured out the height and width of the waterfall you’re going to build, you’re going to need some supplies: specifically, rubber lining (if you’re not using a weir), a pump, large, flat rocks, and piping to circulate the water from the bottom of the waterfall under the rocks or in the pond) back up to the top. The size of the pump is going to depend on the height and width of the waterfall and also the length of pipe from the pump to the top of the fall. You can ask your local dealer or home improvement store employee to supply you with the correct pump. If you have plants or animals in your pond, you’ll probably also want to install a biological filter in the top of the waterfall to keep the water clear and clean of debris.
After you’ve chosen the site for your waterfall and made the decisions regarding the use of a weir, and the height, water volume, and width of the falls, you’re ready to start building. Building might seem a daunting task at first, but don’t worry: it’s a learning process and you will figure things out as you go along.
Step 1: Build the berm.
Start with a surface that is slightly sloped in the back and the same level as your pond in the front. If you don’t have a natural slope to your yard to work with, you can create this one by using the dirt dug up from your waterfall, or you can buy soil from a home improvement store. Often, the dirt dug up from a standard 11' x 16' pond is perfect for creating the slope, or "berm."
Step 2: Lay the liner and install the rocks.
With a weir, the next step is to simply install it in the excavated site, install the pump and tubing, and cover the box with rocks.
If using rocks for the waterfall, line the excavated area where you’re going to put the rocks with a rubber liner, like the one you might have used for your pond. This keeps the water from soaking into the soil below and contains splashing. After the lining is set, get in the pond and start building from the first tier up using large, wide, and flat rocks. Next, install two or three chunkier rocks on top of the first rock. These rocks need to be flat and thin on two sides to support the rest of the rocks that will build up the waterfall more.
Step 3: Finish installing rocks, then position the pump and tubes.
Once the first flat rocks are in place, start building the waterfall up, alternating between spillway rocks and shelf rocks. The spillway rocks are what the water will be cascading from, and the shelf rocks are what hold the spillway rocks in place. Elevate the spillway rocks in the back by using shims, or small flat stones.
After you’ve built up the falls to the desired height and width, you can put the end of the tubing towards the very top of the waterfall with a capstone over the top of it to hide it. Don’t use very heavy rocks as capstone rocks or you will end up flattening the tubing and the water won’t flow very well. When you’re ready to start, plug the tubing into the pump, plug in the cord for the pump, and experiment with the flow of your first design of rocks. It might take a few tries, and some patience, but eventually you’ll get it just right.
How to Build Ponds and Waterfalls: The Complete Guide by Jeffrey Reid.