Deciding what kind of water feature will best suit your needs is not too difficult once you figure out what your priorities for the project are. The following considerations may help you design a water feature that works well in your yard.
There are three basic types of water features you can install in your yard: ponds, water gardens, and waterfalls. If you've never designed or built a water feature, you might not even be sure what the difference between a pond and a water garden is. The differences are slight but can really influence your decision on which feature to go with.
A pond incorporates both fish and plants, which can include goldfish and koi. A water garden is more focused on the plants than the fish. Sometimes a water garden will have goldfish, but koi sometimes eat certain plants, so if the plants are the most important aspect for you, it's best to leave the koi out of it. Then there are reflecting ponds, which are very shallow and won't support water lilies or fish, but can be nice if you just want something small and easy to care for. You can also create a bog pond, which is an area where the soil is waterlogged, creating a suitable environment for growing plants that thrive in moist soil. Waterfalls make a nice addition to any of the above, with the exception of the bog and reflecting pool.
Before settling on the first feature that sounds like it would suit you, flip through a couple magazines or home improvement books that have pictures of different types of water features. A couple good books include The Ponder's Bible by Gosta Lovgren and Water Gardens, Pools, Streams & Fountains by Better Homes & Gardens. Surf the Web to get more ideas about what would look best in your particular yard.
The most important question is which feature will suit your yard and your preferences best? Would you rather relax to the sound of running water, or stare peacefully into the depths of your koi pond? Do you want your pond or water garden to be above ground, or below? Do you have a lot of trees in your yard that could pose a potential problem when their leaves fall into the water? The sections below on designing the perfect water feature can help make your planning a little easier.
The best spot for a pond is on level, well-drained ground. The pond should be installed in an area where runoff from rain won't flow into it, since runoff can carry fertilizers, chemicals, and organic debris into your pond. (However, if you have a desire to "green" your environment, have ample space, and want to do the additional research, you could incorporate a reed bed to treat grey water or run off on its way to your water feature.) Avoid putting your pond in the lowest spot of your yard.
Place your pond where you can access a water and electrical supply—especially a hose to make it easy to add a couple extra inches of water in the summer when it needs it.
Don't place the pond near trees, if you can avoid it. If you have a lot of trees, find a place to position your pond where it won't be in the direct line of falling leaves, which are sometimes toxic to fish and plants. If you position your pond below a tree, you will have to constantly remove the debris from it. If there's no way around putting the pond under a tree, try tying up netting right below where the leaves will fall so they won't pollute your pond. For the maximum plant and fish life, the pond should be in a place that gets approximately 4–6 hours of sunlight a day. However, if you're planning on only having fish in your pond, shade only is okay. A good balance of sun and shade is the best way to keep a healthy pond.
Below-ground gas and water pipes can be a deciding factor in where you put your pond. It's not fun to start digging and hit a gas pipe about halfway through. Many utility companies have a free service where they will come out to your house and tell you where the piping lays. Call before you have your heart set on a location and don't dig without doing this first!
Once you've solved all the practical problems, it's time to work on the aesthetics. A good way to get an idea of your desired shape and size of your water garden or pond is to grab a hose and lay it in different shapes in the area or areas you've picked out. Experiment with bigger and smaller sizes, oval and square shapes, formal and informal. Take pictures, if you want to mull it over.
Formal ponds are geometrically shaped (square, circle) and look distinctively man-made. Use this layout if the rest of your garden or yard is very formal. (Even if you have a cottage garden, you can inject a bit of formality with a geometric pool that can be both unexpected and interesting.) An informal pond is organically shaped and irregular like a natural body of water. Most people go with an informal pond because you can be more creative with the shapes, but formal ponds look beautiful, too.
The most commonly given advice about choosing a size for your pond or water garden is to make it as big as you possibly can. Making a pond a little bigger won't raise the cost substantially. Big ponds are actually easier to maintain, because you can get in them instead of bending over the side to care for your plants and fish. Many first-time water gardeners make their ponds too small and then can't put as many plants and fish in it as they want to. By building the biggest pond you can afford, you'll save yourself the nuisance of not having a large enough pond later on down the road.
If you only want a reflecting pond or bog pond, a foot is deep enough. If you want lilies, you need at least 18 inches. If you want koi, 24 inches is about right. Keep in mind that any pond without fish can house mosquitoes. (There are ways to get around this, such as putting a non-toxic mosquito dunk in the water, but it's nice to have fish as a natural bug repellent). If you want your fish to stay in the water during winter, the pond has to be a foot deeper than your thickest ice. Same goes with the summer—if you're in a hot area you'll need the deeper water levels to avoid killing the fish. Waterfalls can help with heat issues as well. If you live in the South where it gets scorching hot, a 30-36 inch pond is a good idea.
As mentioned before, ponds usually contain goldfish or koi, and water gardens usually just have goldfish if they have fish at all. A pond that incorporates both plants and fish is the easiest to take care of, because if planned correctly the nature will take care of most of the maintenance.
Water lilies are among the most popular plants to put in your pond or water garden. These, along with oxygenating plants and grasses such as anacharis, cabomba, and hornwort are very easy to install and are almost always a staple in healthy ponds. A well-balanced pond will be covered with about 50%-75% lilies and other floating plants. Bog plants are another option; these go in the shallow parts of your pond. Cattails, horsetails and rushes are examples of bog plants.
Most ponds are below ground, but if you want something really simple and relatively shallow, above ground is the way to go. This is also a good way to go if you have really tough soil and it would be really hard to dig the hole. A water fountain set in the center of a brick and concrete reflecting pool would be a good example of an above ground water feature.
There are four different types of pond/water garden liners: flexible liners, natural liners, rigid liners, and concrete. The preformed rigid liner is the only one that doesn't allow the builder/designer flexibility as to the shape and depth of the pond.
Filtration systems are fairly expensive and not always necessary. If you have fish, then a filter is probably going to be necessary. Their waste is composed of ammonia and nitrites, which will kill them eventually if the the pond isn't cleaned up. There are two types of filters, mechanical and biological. Mechanical filters remove the big pieces of junk from your pool using a sponge or matting. A biological filter is a just a box with bacteria in it that will eat the harmful stuff in the water when it passes through. Building your own filter is also an option, and it's really not too hard. You can find ways to build these on ponding web sites as well as in water feature books, magazines, or catalogs.
Waterfalls can be the perfect addition to your pond, and they don't have to be very expensive or time consuming if you're not installing Niagara Falls in your backyard. What you really need to concentrate on for this design project is figuring out the height of the waterfall, and what you're going to use for the materials to make it. Height can be achieved easily by building a berm (i.e. artificial slope) with the dirt you dug up to build the pond, and then placing "spillway rocks" into the berm. A spillway rock is a long flat rock that the water spills over, creating the waterfall. The other way to go is to buy an artificial wall for the waterfall. These can be found at any home improvement store. Or bypass the berm and just use rocks to create your perfect waterfall.
How to Build Ponds and Waterfalls: The Complete Guide by Jeffrey Reid.
Adding a water feature can be a big job especially if it's complex. For assistance, a licensed landscape architect through ContractorNexus can help design a solution that is ideal for your yard.