How To Build A Koi Pond With A Waterfall

A koi pond with a waterfall brings a peaceful beauty to a garden, with the Koi gliding elegantly through the water and the waterfall tinkling melodically over the rocks. You may think that a pond like this only comes with a mansion you can’t afford, but building your own DIY Koi pond is easier and less expensive than you realize.

To build a Koi pond, you will have to dig a hole and line it with underlay and pond liner. Build steps for the waterfall with a top reservoir and lay the liner where the water will run. Run the return tubing from the pump to the reservoir, disguising construction and equipment with rocks and stones. 

Building a DIY Koi pond with a waterfall may be a bit labor-intensive, but if you’re not afraid of hard work, it will give you an immense sense of satisfaction and a peaceful and scenic corner to your garden. Add a garden bench or swing, and your family will fight for the spot when they want to take some time out.

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Steps For Building A Koi Pond And Waterfall

Before building a Koi pond in your garden, there are some points that you need to take into consideration. 

Step 1: Digging And Sculpting The Koi Pond

Though your pond may not be a failure, in the end, you could save yourself a lot of work by doing your research and planning the pond carefully. Decide where you will build the pond, and if it has a hill, it will save you some effort when building the waterfall.

First, dig out the outline of your pond according to the size necessary for the number of Koi you will have. The hole should be at least 3 feet deep to protect them from being eaten by birds. You can build a shallow step around the edges to house potted plants. If you want a deeper pond, dig the sides out in steps to provide stability.

If you’re not building your pond near a hill, you can use the dirt that you dig out for the pond to create one for the waterfall, so shovel it onto the waterfall spot as you dig. 

Step 2: Lining And Preparing The Koi Pond

You need to line the pond with a 45-mil EPDM rubber liner. It’s a good idea to use underlayment beneath the liner to protect it from getting punctured by any remaining stones and roots. Commercial underlayment is available, but you can cut expenses using an old carpet. Once you have lined the pond, pack heavy rocks on top of it.

Step 3: Building The Waterfall For Your Koi Pond

You can build the waterfall in two ways: using the dirt you dug out from your pond or building steps out of cement, concrete blocks, or large rocks. Lay some rubber liner in the channel that flows into the pond. Cut enough liner to hang over the edges by a few inches and allow the pond liner to go over the last step of the waterfall.

Place your pump inside the Koi pond and take the return tubing up the steps to the top reservoir. Cover the areas alongside the waterfall liner with smaller rocks and take large stone slabs for the steps. Lay the rocks from the bottom upwards, with your large flat rocks supporting the spill stones, which slope down to the pond. 

Pack the waterfall rocks artfully next to the channel. Be creative by varying the rocks’ shape, color, and size. Cover the area above the spill stone and under the rocks at the bottom of the waterfall with a layer of small river stones. The idea is that the pond looks as natural as possible.

Step 4: Equipment For The Koi Pond

You will need some equipment for the maintenance of your Koi pond. A pump and filtration system are both necessities. Make sure that your filtration is adequate for the size of your pond and the number of Koi you will have. The recommended way to do this is to purchase one for double the volume of your pond. It is advisable to have both mechanical and biological filters for Koi.

Skimmers will also help maintain the clarity of the water, and we recommend adding an air pump to oxygenate the water. Nitrifying bacteria that keep the water properly clean need oxygen to do their job.

How Soon Can I Add Fish To My New Koi Pond

Wait approximately 72 hours before adding your brand new Koi to their new home. Check that the pH level is between 7.2 and 7.8 for nitrites and ammonia as these are harmful to Koi and other fish. You should also see that the water temperature is at least 60°F before adding your Koi.

The water temperature should not be more than 15 degrees different from the Koi’s current water. Let the Koi float in a bag with its previous water for about a half-hour. Adding water from the pond into the bag will allow the fish to adjust to the temperature and convey information about the pond and other fish to the new addition. This helps the fish to acclimate as well. 


Building a Koi pond with a waterfall is a lot of hard physical labor, but it is not difficult. If you take your time planning and not taking shortcuts, you will soon have a beautiful addition to your garden, adding value to your outdoor time and to your home.

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