Posted by Brent Wilson on 9/29/2016 to DIY Projects
So you're thinking about building a garden pond? It's really not too difficult to build one yourself. A pond may offer a number of benefits. It can be cool and relaxing, visually appealing and it can provide the local wildlife a watering point. Aside from the enjoyment, it can increase the value of your property.
Building an in-ground garden pond is much easier than you think, I've built hundreds of them. But, before you start digging, there are some things you'll need to consider...
It is important to know the reason why you are building this pond before the actual construction. Before you build your garden pond, it's best to have a well thought out plan. Have you decided on the location?
Location is important
Where will you're garden pond be located? You'll probably want to put your garden pond in a location where it can be viewed and heard from as many points as possible: near a patio or deck, an outdoor living area, or a location from where it can be viewed and heard through windows from inside the home. Look for an area that offers a slope. Slopes are perfect for use as a backdrop, and as a foundation in constructing your waterfall.
Size is important
Do you want a mini-lake out back, or a smaller garden pond off the back patio? Do you want a waterfall, and if so, how big and how tall? Do you want a raging river, or just a simple stream or trickle of water over the waterfall? I recommend a size that fits with the size of your property. A raging river looks out of place in a small back yard. On the other hand, a very small pond looks like a little puddle on a large property.
If you want to grow water lilies or other sun-loving aquatic plants, choose a sunny site that provides at least 6 hours of direct sunlight. If your pond will be shallow, it is best to provide afternoon shade as it can over heat during mid afternoon. If you aren't concerned with growing flowering plants in the pond, a shady spot is fine.
If your pond will have a waterfall, fountain or lights it will need electricity - so locate your pond accordingly.
Ponds must have an overflow area, which is a low point to control where the excess water should flow out of the pond when there is heavy rainfall.
Temperature extremes should be minimized in the pond. If you intend on raising and keeping fish, it is important to make the pond as deep and as large as practical. However, deeper ponds may need to be fenced to prevent accidents.
Waterfalls and streams are cool
If you want a raging river that splashes over Mount Everest, or a stream that connects two ponds, and you have very little or no experience in the construction of a garden pond, we suggest you contact a pond professional. Otherwise, small waterfalls and other features that are easy to build. You'll find instructions further below.
Plants and fish
Do you want lots of larger fish such as Koi, smaller goldfish, or no fish at all? Koi grow large and will need a larger pond. Goldfish stay smaller so are best for smaller ponds. Do you want plants growing inside the pond, and if so, what types?
Have you decided what type of liner? Choice of pond liner will be a flexible one, no pun intended. Your basic choices will be between flexible and preformed rigid liners. I much prefer a flexible liner because it allows you to design the pond any shape you like.
Before heading off to your local pond supply store to buy materials first draw a simple sketch on paper of the general shape you want for your garden pond. Note the length, width, depth(s), and height of waterfalls on your sketch. This will help your local pond store professional advise you on the materials required. As a general rule, a 180 square-foot or 10' x 15' pond is a good "standard"" size water feature. However, build whatever size and shape you want if you'll be using a flexible pond liner. Include in your sketch where the waterfall(s) will be located.
How To Build a Garden Pond
Though many of your own smaller creative decisions will be made during the process of building your garden pond, below are some general guidelines you can follow for construction of a small garden pond.
Tools You Need:
- Round and flat point shovels
- Carpenters level
- 2x4" stick of lumber 8' or more in length
- Can of orange spray paint (marking paint)
- Pruners to cut through small roots
- Wheelbarrow, maybe
- Leather gloves
- Measuring Tape
NOTE: The instructions provided below assumes you will be using a flexible type liner, such as 45 mil rubber liner.Step-By-Step Instructions
STEP 1: Outline Shape
Begin by using marking paint, or lay out a garden hose, to outline the shape of your pond. This outline should be the perimeter shape of the water surface area.
Most pond excavations have flat ledges - called "plant shelves" - at different depths all around the perimeter. These plant shelves allow for the placement of different types of plants that require different depth levels to grow properly. Paint out these lines for shelves as well. You'll want a deeper area (24-36") for fish to hide and stay warmer during winter. Then a shelf level at 12-24" deep for certain plants, and another shelf level at 6-12" for certain other plants. If you look at the picture below, you'll notice I left an area to the far left that is very shallow. When the pond is filled with water, this area might be two or three inches deep. This is for animals and birds to use as drinking and bathing source.
Caution: If you have even the slightest suspicion that you will be digging near buried cables make sure to call your local utility companies to have the location of these cables marked before digging.
STEP 2: Excavation
Now that you've outlined your pond excavation may begin. Start by first digging out the deepest section of your pond. If you plan to have fish, make sure to dig one section of the pond at least 24-30" deep by 18" wide to provide a safety zone if predators come around. Dig this hole in a central location within the perimeter of your pond. Post hole diggers or a trenching shovel may be necessary for digging narrower holes.
If the ground area around your garden pond is flat, you can use the excavated dirt to build a mound(s) that will serve as the foundation where your waterfall(s) will be located, as seen in the picture above. Build the mound for your waterfall anywhere from 12 to 36" in height. Likewise, additional excavated dirt can be used to create a low raised berm around the entire pond. This helps prevent backflow from entering your pond water when there is heavy rainfall.
Note: Before installing your liner. You will need to flatten the tops of the berms so that stones will lay flatly upon them.
If you are building your pond into an embankment, pile the excavated dirt around the lower side of your pond forming a berm that will be equal in height with the base of your waterfall(s). This will ensure that when you fill your pond with water, liner won't show on the side where your waterfall is located.
After digging out the deepest area of the pond (24-36" depth), work outward digging the next level to 18" depth, and then the next to 12" depth.
Tip: If you plan to use a submersible pump, and would like to make sure that it is hidden from view, excavate an area that will be underneath the base rock of your waterfall. This area should only be wide and deep enough to house your pump and the container or pot that you will enclose it in.
STEP 3 - Remove Debris & Smooth
After excavation is completed, remove any rocks, sticks, and other debris that might poke a hole in or cut your liner. Smooth all surfaces with your hand. If you want to be on the safe side, line the floor and interior walls of the pond with an inch or two of sand, a 1/4 -inch layer of newspaper or carpet, or a couple layers of landscape fabric.
STEP 4: Measuring for Liner
Liner size is calculated based on the width, length and depth of the excavation, the size and number of plant shelves, and the amount of edge overhang, so the sizing will be more accurate if done after the excavation is complete.
To measure for your liner, use a sewing or construction measuring tape. Start by measuring the length at the widest point. Place one end of the measuring tape at a point 12-18" outside the perimeter of the excavated hole, or beyond the base of a berm if you built one. Press the measuring tape against the ground, going over berms and down through the excavated hole and back up over the other side to a point 12-18" beyond the perimeter of the excavation or base of a berm. Make sure measuring tape is always contacting the soil over any shelves and levels. Write this measurement down. Do the same for the width.
Note: To ensure your pond liner will be large enough, you may want to add an extra foot or so to both the length and width. You can always cut to reduce the size of a liner but you can't make it larger!
So that you'll know how many gallons of water your pond will have when filled, take several measurements of the various depths of your pond. Note the width and length of the areas at the various depths as well. Write these measurements down on your design if you did one. Also measure the height of your waterfall. These measurements will allow a pond store professional to determine what size of pump will be necessary for your waterfall.
Note: If you will be constructing a tall waterfall, over 24' in height, additional measurements will need to be taken in order to purchase an addition liner to cover the foundation of your waterfall. Measure height of waterfall so that your waterfall liner will extend from a point beneath the waterfall, to a point where your liner will drape over the back and down to ground level.
STEP 5: Purchasing Materials & Supplies
You want to wait until the excavation is completed and the measurements mentioned above have been taken before purchasing the pond liner, pump, filter, and other supplies.
STEP 6: Installing The Liner
Before installing the liner, make sure you have flattened the top of any perimeter soil berms. If you did not fill excavation with sand and/or carpet, make sure that any stones or other sharp objects have been removed. Rub your hands over the surface of the soil to make sure everything is smooth.
With a couple of people helping, the liner is unfolded into the excavation. It's best to do this with bare feet, or soft-soled shoes. The liner is then smoothed into place from the center-bottom up, and is lapped over the top edge of the pond 6 to 12 inches. A small amount of water is typically added to the bottom of the pond to weigh the liner down and help with the smoothing process. Folds in the liner, which will be necessary to help it conform to the curves of the pond sides, are incorporated as the liner is smoothed out.
STEP 7: Place The Pump
Place the submersible pump in the bottom of your pond (or in the cavern you built under the base rock of the waterfall). Attach tubing and drape over the waterfall foundation.
STEP 8: Install The Filter
A filter is optional, however, if you want to keep your pond water clear and free from algae, a filter that contains a UV light is highly recommended.
There are filters that you can place within your pond, or those that can be installed outside the pond. I like using the one's that go outside the pond. The filter will have an intake and an outflow. You will run a hose or tube from your pump to the inflow on the filter. Then you will run a hose or tube from the outflow that will go to the top of your waterfall.
STEP 8: Install Any Interior Rocks
Once the liner is in place, and your pump and filter have been installed, if desired, you may begin to add rocks or small boulders to the INTERIOR of the pond. Rocks that will be placed beneath the water surface should be washed and scrubbed thoroughly to remove all dirt and other particles.
STEP 9: Add Water
Now you can begin to add water! It could take some time to fill your pond with water using a garden hose.
Note: Scroll down for detailed instructions for constructing a waterfall
STEP 10: Placing Rock
While the pond is filling, use the time to begin placing exterior rocks around the perimeter of you pond, including the ones that will serve as your waterfall. Start by placing flat stones around the perimeter of your pond and the rocks that will serve as the base of your waterfall(s). Allow these flat stones to hang a little over the edge of where the water will be when the pond is full.
Then place rocks or boulders of random size and shape atop the flat stones.
Make sure the liner, pump and tubing for the waterfall are all in place. See detailed instruction for building the waterfall below.
Add plants in and around your pond, mulch around the exterior plants, and continue to fill your pond with water. When the pond is full of water all that's left to do is turn on the pump!
How To Build a Waterfall
Outdoor waterfalls come in all shapes and sizes and make for emphatic focal points. When mulling over your design options, the main consideration is how to achieve the necessary height and overall size for the waterfall. Too, you will need to select the type of stone or other material that will be used to construct the waterfall. Select materials that will fit in and compliment the surroundings.
Waterfalls can be simple or elaborate, designed to empty into a single pool or pond of water, originating from a flowing stream and falling through several tiers, or cascading dramatically from many feet above the ground. In planning to build outdoor waterfalls, you need to concentrate on two structures:
- The pool into which the water falls
- The cascading structure for the waterfall itself
Once these two structures are in place, you'll use a pump, inside or outside the pond, to keep water recirculating from the pond to the top of your waterfall, where it can plunge back down splashing into the pond.
Designing The Waterfall
The size of your waterfall is something to be considered. Design your pond to match the size of your outdoor space; not too big, not too small. Accordingly, design your waterfall to match the size of the pond it will spill in to.
In building you waterfall, you should use top quality materials. The little extra money spent will save you replacement costs and maintenance headaches in the future. The amount you will need to spend for construction will depend on the overall size of the pond and waterfall. Whatever you do, do not skimp on the pump that will generate the moving water over your waterfall and into the pond. To build a reliable and beautiful waterfall you will need the right rocks (in the right places) and lots of moving water.
Waterfalls can be constructed atop level ground by using the dirt dug from the pond to create a berm aside/behind the pond. If you are lucky enough, your waterfall can be built into an existing slope on your property. Either way it will require some work. You will need to lay a flexible liner beneath the stones used to construct the waterfall. This liner should drape over the backside of the berm or go above the top rock on a slope and at the bottom should drape over the liner used in the pond so no water can escape.
Most likely, you'll be building the waterfall with rocks. One alternative to using natural rocks placed atop a liner for a waterfall is to use pre-cast concrete forms that mimic stone for the cascading structure. They're compact and easy to install, but you'll have to decide if these look natural enough for your taste. They are not natural enough for mine.
If you go the natural route, the most important rocks are what might be termed the "spillway" rocks. "Spillway" means the rocks directly over which the water will cascade. In a cascade design you will use two or more rocks, one above the other, and so on, as shown in the picture below.
Note: Before laying the liner you should stair-step the face of your berm for the waterfall. This will allow you to place the back edge of your flat cascade stones flatly. The front edge of the cascade stones can be held up and adjusted for water flow by placing small rocks or flat bricks between the cascade stones.
As shown in the picture below, you can use bricks or flat stones as spacers between the spillway stones in your waterfall. If these are visible after completion, you can hide them by placing smaller, natural stones in front of them.
Picking Out The Spillway Stones
Unless you're lucky enough to have large flat stones on your property, you'll need to visit your local stone center to look at and select rocks. Start by picking out mostly flat rocks to construct the waterfall. Select one larger and thicker flat rock for the base of the waterfall and several other larger flat rocks for the tiers. For the rest of the structure a mixture of sizes and shapes is fine.
Note: The rocks used in the waterfall, which will come into contact with spilling or trickling water, should always be angled slightly forward so that the moving water moves in the right direction: towards, and into your pond!
The idea behind selecting spillway rocks for a cascade design is to choose rocks that are most likely to channel the falling water in the precise direction in which you want it to go. In addition to seeking out relatively flat rocks with sharp edges, see if you can find rocks that are slightly cupped. Occasionally you'll come across flat rocks that curl up ever so slightly at the edges, leaving a depression in the middle. The natural channel in such rocks will be greatly advantageous for the creation of the spillways in your cascade design.
Load your rocks up or arrange to have them delivered, and now you're ready to head over to the pond supply store to purchase a pump, filter and other supplies.
Calculating Water Volume
Before choosing a pump and filter for your pond and waterfall, it's a good idea to calculate the volume of water in your pond. This is not absolutely necessary for you to do, but the measurements in the equations below will be useful to your pond store professional. You don't have to be exact with your measurements, just close.
Rectangular Pond: Length in feet x width in feet x depth in feet = total cubic feet. There are 7.5 gallons in one cubic foot. Example: the equation for a pond that is 10' long by 6' wide by 2 feet deep would look like this:
10' L x 6' W x 2' D = 120 cubic feet x 7.5 gallons = 900 gallons
Circular Pond: 3.14 x radius x radius x depth = cubic feet. Example: If the diameter of your circular pond (from one side to the other) is 10 feet, that means the radius of your pond, which is half the diameter, is 5'. So the equation would look like this:
5' W x 5' L x 3.14 = 78.5 x 2' D = 157 cubic feet x 7.5 gallons = 1,177 gallons.
Free Form Shapes: Break the pond down into a series of rectangles and circles and figure the volume of each area separately, then add the volumes together.
Note: Each cubic foot contains 7.5 gallons of water, so always multiply the total number of cubic feet times 7.5 to determine the total number of gallons. Write down the total volume of water your pond contains. And remember, you don't have to calculate water volume. If you have the basic measurements as to width, length and depth of your pond, this will be enough information for your pond store professional.
Plumbing For Your Waterfall
First, you will want decide the effect of your waterfall. This will help you determine the amount of water flow you need and the size of pump and filter that will be necessary to create the desired effect. Some like to create a raging waterfall while others prefer the trickle effect. The plumbing for either choice is quite simple and you should have no problems handling this yourself.
Pumps are available in both submersible and external (out-of-pond models). Reputable water garden suppliers have charts and other information available that can help you select the best model and connecting equipment for your purposes. For the smaller pond, a submersible pump is the most economical. Depending on the size of the pond, a filter and even a skimmer may also be incorporated.
Submersible Pumps are placed directly in the pond. They are free of distracting noise and can be used to drain your pond when necessary. Some submersible pumps do have a disadvantage. The pump seal can rupture, sending oil coolant into the water. This can prevent surface gas exchanges, thereby endangering your fish. I would recommend the new magnetic-drive pump, which avoids the use of coolants. They are more expensive to buy but are far less expensive to operate.
Pumps come in a confusing array of models and sizes. Below is information that will help you determine what size of pump you will need for your pond or water feature.
If you find the following confusing, don't worry, just take recommended measurements to your pond supply store and a professional can help you figure out what type and size of pump will be required.
Smaller pumps are sized by gallons per hour (GPH) output at one foot of lift or height. Larger capacity pumps are rated by horsepower (hp). Manufacturers offer charts that break down the power of each size pump according to incremental heights of one foot. Some companies label pumps by GPH while others assign letter or number designations that require cross-referencing to charts.
Note: Pumps come with flow valves so that you can adjust the amount of flow to achieve just the right effect.
It is recommended that the water in a basic pond be turned between 1/2 to 1 times per hour. A 500-gallon pond should have at least a 500 Gallon Per Hour pump. When sizing a pump for a pond there are a few other considerations.
- How high will the pump have to lift water?
- Will there be a fountain?
- Will there be filters?
Important Other Measurements
Estimate the vertical height from the top of your pump to the top of your waterfall or stream and write this measurement down. Add another foot of height (or lift) for every 10 feet of hosing you will be using and write this measurement down.
If you plan to have a stream a general rule of thumb is to figure your stream/waterfall requirement as 150 gallons per hour per inch width of the spillway or channel. For example, if your stream or waterfall spillway will be 10 inches wide, you will need a pump that produces a flow of 1500 gallons per hour (at whatever combined height of the feature and another foot of height for every ten feet of hosing to get there).
This may sound a bit confusing so just write down all the measurements (heights and widths) you can think of so that when you consult with a professional he/she will have these measurements to assist you in determining the size pump you need.
Note: It is best to order a pump that will more than handle your needs as pumps come with valves that allow you to reduce the amount of flow.
Don't let any of this technical information about pumps scare you away! A few simple measurements you take can provide your pond supply source or local pond consultant with the information needed to assist you in choosing the right pump. Just remember this: DO NOT skimp on the pump!
After selecting a pump to create the desired effect for your waterfall, you will then need to select the appropriate size piping to match the pump.
In the same way you measure for a liner, measure the distance from where your pump will sit in or outside the pond and where it will travel to the top of the waterfall.
Recommended tubing diameter for pumps to waterfalls:
- 1/2-inch diameter for flows up to 120gph
- 3/4-inch diameter for flows up to 350gph
- 1-inch diameter for flows up to 1000gph
- 1 1/4 inch for flows up to 1500 gph
- 1 1/2 inch for flows up to 3000 gph
A well designed larger pond should include filtration. Ask your pond supplier about a filtration system that will work well with the pump you select. You can choose from submersible or exterior filters. I recommend choosing one that has a UV filter to reduce or eliminate green algae formation in the water.
Pumps can be custom ordered with cords of various lengths that can be plugged into ground fault outlets from your home or other nearby structures or buildings. If your pump is too far away from an outlet you may need to hire an electrician to install a ground fault outlet closer to the pond. Make sure to install an electrical outlets at a distance greater than 6 feet away from the water in your pond.