How to Build a Koi Fish Pond Step-By-Step

How to Build a Koi Fish Pond Step-By-Step

As a symbol of calm and serenity, koi fish ponds make the perfect addition to any outdoor sanctuary. When building your own koi pond, there are some considerations you need to make and a series of steps to follow. A koi pond can be built using a wide variety of materials. Further, they can be built in-ground, on the ground, or even a combination of both. While no two koi fish ponds are exactly alike, they all share some common fundamentals. Today, Koi Fish USA will be talking about these common fundamentals as well as how to build a koi fish pond step-by-step. We hope that this information will prove helpful in guiding you along the process. Let’s get started!

What Do All Koi Fish Ponds Need?

Before building your koi fish pond, you should be aware of the essentials. While koi fish ponds differ in size and aesthetics, all koi fish ponds require some common equipment and fundamentals. Here is a list of the equipment and standards you’ll need to purchase and keep in mind when building a koi fish pond:


  • A pond skimmer (optional)
  • A backwashable mechanical filter
  • A biological filter 
  • A bottom drain (optional)
  • A bottom drain pre-filter (optional)
  • A water pump
  • Water circulation and turnover rate
  • An aeration system
  • A depth of at least 3-4’
  • A UV clarifying system

Steps to Build a Koi Fish Pond

Now that you know the fundamentals that all koi fish ponds require, it’s time to get to building your own koi fish pond. By following this series of steps, you can create a koi fish pond that offers all of the benefits you’re looking for. If you follow these recommended steps carefully, the result will be a koi fish pond that you and your family can enjoy for years to come, teeming with healthy and happy fish.

1.   Select the Best Place for Your Koi Fish Pond

The first step to follow when building a koi fish pond involves selecting the best location for your pond. Think about what you want out of your pond. If you want to be able to easily enjoy your pond, it’s best to place the pond close to your house for the most convenience. You should also consider the fact that koi fish ponds tend to do better in shaded areas than in direct sunlight. While full sun won’t necessarily harm your koi fish, this raises the water temperature and leaves you with more work to do to properly maintain the right temperature.  A shaded area will also generally slow down algae growth. In most cases, people also want their koi fish pond to be positioned in a place where they can see it from both inside and outside their house. Take this into consideration when choosing the right location for your koi fish pond.


You should also take into account the fact that pond maintenance will be much more manageable if you pick the right location for the pond. Ponds built underneath trees, for example, bring more shade but will be a nightmare in terms of cleaning up leaf litter and debris that land in the pond. Additionally, ponds that are installed in low-lying spots are subject to pollution and flooding during storms.

2.   Determine How Big You’d Like Your Koi Fish Pond to Be

Once you’ve determined where your pond will be located, the next step is to determine the appropriate size for the koi fish pond. To make things easier on yourself, take some time to trace out your preferred size on the ground. One of the most common mistakes that people make when building a koi fish pond is that they build it too small.


Keep in mind that, for koi fish, the smallest recommended building is approximately 1,500 gallons and at least 3-4 feet deep. While this may sound like a large pond to some beginners, most people who already have a koi fish pond of their own will agree that if your pond is smaller than that, you won’t be happy with it. Further, your koi fish will need room to grow and enjoy life so making your pond larger rather than smaller is the appropriate route to take.


You should also keep in mind that the more fish you’d like to keep in your pond, the larger your pond will need to be. A 1,000 gallon pond that is at least 3-4 feet deep, for example, should house no more than five average size koi fish. More fish than that will require a larger pond. If you plan on housing up to fifteen koi fish in one pond, you’ll want a pond that is roughly 3,000 gallons.

3. Excavate Your Pond

Now that you’ve picked the right location and appropriate size for your koi fish pond, it’s time to dig! Before digging, however, you’ll want to outline the pond perimeter and detail areas where components like the pond skimmer, falls, and filtration will be placed by using marking paint. Begin your excavation by digging tiers/shelves. The bottom tier should be at least 4 feet deep in order to accommodate your fish over the winter months.


We recommend starting the excavation process with a small excavator as they will easily dig holes for the pond. The excavator should be used to do the “heavy digging” before fine-tuning the excavation by hand with shovels. To allow for construction of any retaining walls, ensure that the excavation is at least one foot longer in every direction.

4. Select your Filtration and Water Circulation System

The next step in building a koi fish pond involves selecting a Filtration system and water circulation system. You will need a pump to circulate the water through the filtration system. Your filtration system must consist of both a Mechanical filter to remove debris and solids from the water and a Biological filter to remove harmful Ammonia. Koi fish Ponds require a certain necessary type of bacteria to convert harmful Ammonia into Nitrates.  A Biological filter is designed to help this special type of bacteria thrive. Typically, people use bacteria tanks as part of their waterfall to run over rocks and into the koi pond. Either a waterfall or some other type of water circulation system is required to keep the koi healthy. You can even use the dirt from the hole you excavated to use as a base for the pond’s waterfall.

5. Cover Your Newly Dug Hole With a Liner

Next, it’s time to add your pond’s liner. The liner should extend approximately a foot out of the hole that you dug. You can anchor your liner with large rocks. Smooth out the liner as best you can and, when walking around in the pond, be sure to tread carefully so that you don’t rip the liner.  The best liner to use is made of 45mm EPDM rubber, similar to rubber roofing but specifically designed to be fish safe.  Rubber roofing contains algaecides and other chemicals which may be harmful to your fish.

6. Install Your Pond’s Water Pump

When purchasing a water pump for your koi fish pond, you’ll want to make sure that the pump has enough water to supply the size of your pond. All ponds and waterfalls require a circulating pump. These pumps come in various sizes according to the speed you need to pump the water and how fast you want the flow rate to be. We recommend circulating your water no less than once per hour however 2-3 times or more per hour will keep your pond cleaner.

7. Install Your Pond’s Water Filter

Once the water pump is installed, you’ll want to install your pond’s water filter. The filter is the heart of the koi fish pond. The water filter is responsible for keeping the water clear and healthy for your koi fish. There have been many koi fish ponds in the past that have failed all because owners elected to spend all of their money on the aesthetics of the pond and save money on the filter. This isn’t the place to cut corners.


Your water filter will serve two purposes. For one, it serves as a mechanical filter that removes fish waste and toxins that could cloud the water. Secondly, it serves as a biological filter that converts the ammonia produced by the fish into nitrites which eventually turn into nitrates that are harmless to koi fish. If you want to make sure that your koi fish thrive, selecting the right water filter is essential!

8. Fill With Fresh Water

Once all of the appropriate equipment has been installed in your koi fish pond, it’s time to fill it with fresh water. During the filling process, you’ll want to make sure that your pond retains water before adding any plants or fish.  If you are filling with water from a public municipality be sure to use a dechlorinator before adding any fish.

9. Add Plants to Koi Fish Pond If Desired

For those who favor making their koi fish pond as beautiful as possible, this is an enjoyable step to building a koi fish pond. Some people will argue that you must have plants in your koi fish pond to consume the nitrates as they build up. Fortunately, all of the algae that naturally forms in the pond feeds on nitrates the same as plants do. It is recommended that a healthy pond develop a ¾ inch layer of green algae on the inside walls of the pond. This means that your koi fish pond’s plants are largely there for aesthetic value.


There are several options to choose from when deciding on which aquatic plants to put in your koi fish pond. These can be divided into 3 main categories:


  1. Floating plants: Water hyacinths, water lettuce, water lilies, lotus, etc..
  2. Submerged plants: Fanwort, American waterweed, water purslane, etc..
  3. Shallow-water marsh plants: Umbrella plants, water iris, horsetail, etc..

10. Add Your Koi Fish at the Proper Time

With your pond fully constructed, it is likely that you’re anxious to add your koi fish! That being said, if your pond is retaining water, you should wait a few weeks before introducing your koi fish into the environment. This is because it’s important to let your pond circulate and build up some sediment before adding your koi fish.


You should also ensure that your water is healthy before adding your koi fish. Chlorine is unhealthy for fish so try not to fill up your pond with chlorinated water. If it is chlorinated, like most tap water, be sure to use a dechlorinator. You’ll also want to check your pond’s pH, which should be between 7.2 and 7.8. Finally, wait until your water temperature is between 65 and 75 degrees Fahrenheit, the recommended temperature for healthy koi fish.

Fill Your Pond With Koi Fish From Koi Fish USA!

Now that you’ve constructed a beautiful koi fish pond, you’ll need to supply it with healthy, stunning koi fish. If you’re wondering where to buy your next koi fish, wonder no longer! Koi Fish USA is the country’s best supplier of beautiful and healthy koi fish. With over 25 years of combined experience in the online koi and goldfish industry, we are the experts you can rely on. We have a passion for providing the safest, most high-quality koi fish on the market, all at a price to suit your budget! Check out our selection today!