How To Build A Koi Pond In 12 Steps

There’s something about a koi pond that instantly creates a feeling of peace and tranquility. Keep reading to learn how to build your own koi pond in 12 steps, and get started on your very own backyard oasis.

How To Build A Koi Pond

1. Plan Ahead

How to build a koi pond like this

Building a koi pond is a great way to add beauty and interest to your yard. It can provide a fun and relaxing place to be for your family and guests. However, before you start digging, there are a few things you need to plan in order to ensure a successful project.

Pond Location

The first step in how to build a koi pond is to choose the location. When you’re choosing a location, there are a couple of things you’ll want to keep in mind:

Sunlight: Koi ponds need to be in full sun for at least six hours per day. Koi are cold-blooded animals, so they rely on sunlight to warm up their bodies.

Avoid Trees And Bushes: You’ll want to make sure that the location you choose is not too close to any trees or bushes. Although you don’t have to absolutely avoid trees and bushes, it does cut down on the amount of maintenance you will have to regularly perform.

Leaves falling into your pond can create problems, from clogging up your filter to polluting the water. Shade from large trees can also prevent your koi from getting enough sunlight. This is why it’s such an important step in how to build a koi pond.

Pond Shape

One of many pond shapes

There are many factors to consider when deciding on the shape of your pond. These include the size and layout of your yard, the number and type of fish you plan to keep, and the overall aesthetic you’re going for.

Here are a few common shapes people consider when researching how to build a koi pond:

Oval: One popular option is the classic oval shape. This is a great choice if you’re looking for a pond that’s simple to construct and easy to maintain.

Rectangle or square: If you have a smaller yard, you might want to consider a rectangular or square pond. These shapes are perfect for tight spaces and can still accommodate a good number of fish.

Circle or hexagon: If you’re really looking to make a statement, you could go for a more unique shape, like a circle or hexagon. These ponds can make the process of how to build a koi pond more challenging, but they can add an element of interest to your landscape.

Pond Depth

Example of pond depth

There are a few things to consider when deciding on the depth of your koi pond.

Climate: You need to consider the climate you live in. If you live in an area with hot summers, you’ll want to make sure your pond is deep enough so that the water doesn’t get too warm. A depth of 4 feet is generally considered the minimum for a koi pond in a hot climate. In a milder climate, a depth of 3 feet may be sufficient.

Fish size: You need to consider the size of your fish when thinking about how to build a koi pond. Koi can grow quite large, up to 3 feet long in some cases. As they grow, they’ll need more space and deeper water to swim in. If you plan on keeping large koi, you’ll need to make sure your pond is at least 6 feet deep.

Aesthetics: You need to consider the aesthetics of your pond. A deeper pond will usually look more attractive than a shallow one. If you want your koi pond to be a centerpiece in your backyard, you’ll probably want it to be at least 4 feet deep.

2. Utility Locations And Permits

Call 811: This may be one of the most important steps in how to build a koi pond. Once you’ve chosen the perfect spot for your koi fish pond, it’s time to start preparing the area. But before you grab that shovel, call 811 to ensure you aren’t digging in an area with any underground utility lines.

Permits: Check with your local building department to see if there are any special requirements for constructing a pond in your area. Depending on the size and intended use of the pond, you may need to obtain a permit. It’s also a good idea to check with your HOA, if applicable.

3. Outline Your Pond

This is another part of the planning part in how to build a koi pond. Using a garden hose or string, mark out the shape of your pond. This is a good time to experiment with different pond shapes if you want to get a better idea of how a particular shape will look on the ground.

4. Dig The Pond

Digging a backyard pond

Now it’s time to dig! Depending on the size of the pond you are digging, you can do this with a shovel or use heavy equipment like an auger.

Avoid creating steep vertical sides. Instead, when doing this step in how to build a koi pond. Create a shelf around the edge of the pond for planting marginal aquatic plants. The shelf should be about 12 inches wide and 18 inches deep. Depending on the size of your koi pond, you may be able to create multiple tiers.

5. Install The Drain (Optional)

Pond drains circulate water and help remove biological waste. However, a drain is not always necessary for a koi pond, especially if you have a sustainable ecosystem and other filtration systems in place. If you do opt to install a drain, make sure you dig a trench for the pipe or tubing so it isn’t pushing up against the pond liner.

When installing the drain as part of how to build a koi pond, be sure to use PVC pipe or flexible tubing that is at least two inches in diameter. You will also need to install a check valve to prevent water from flowing back into your pond. The pond drain hose will then connect to a settling chamber that sits in an in-ground chamber or tank.

6. Lay Down The Pond Liner

Pond liner laid down

Before you lay down the liner, remove any rocks, roots, or other debris that might puncture the liner. Start by unrolling the liner (there are several different types of pond liners available, but EPDM is one of the most commonly used). It’s also a good idea to get someone to help you since pond liners can be quite bulky. This is why it’s good to have a partner during each step of how to build a koi pond.

Start at one end of the pond and work your way around, making sure that there are no wrinkles in the liner. Ensure you leave approximately 1 foot of liner beyond the edge of the pond to allow for soil settlement. When you get to the other end of the pond, cut off any excess liner and secure it in place with some heavy rocks.

7. Add Rocks And Gravel

Adding rocks to a pond

Add a layer of coarse gravel over the liner. It’s important if your how to build a koi pond process involves making it an ecosystem pond. This will provide a stable base for the larger rocks or boulders you’ll be adding on top. Be sure to use rocks that have been washed prior to adding them to your pond water. Unwashed rocks can contain harmful bacteria or chemicals.

Then add the desired amount of rocks on top of the coarse gravel layer. Be sure to leave enough space around the edge of the pond for plants or other decorations.

8. Install Pump, Filters, And Other Equipment

This equipment is essential in how to build a koi pond because it lessens the maintenance and keeps everything running.

Pump: The size of your pond will determine the size and type of pump you need. The pump is responsible for circulating the pond water and keeping the water oxygenated. Ensure that the gallon per hour (GPH) rate for your pump circulates the entire water volume of the pond every couple of hours.

Filters: Koi ponds need pond filtration systems to keep the water clean and healthy. This is critical for how to build a koi pond to keep your fish healthy. There are a variety of different filter types available, but we recommend using a combination of mechanical and biological filters.
– Mechanical filters (such as a pond skimmer) remove physical debris from the water.
– Biological filters remove harmful toxins and waste products.
By using both types of filters, you’ll create a cleaner and healthier environment for your fish.

Aerators: Aeration helps to keep the pond water oxygenated and prevents stagnation. There are several different ways to add aeration to a koi pond, but one of the most popular methods is to use an aerator. 

Other optional equipment to add as part of how to build a koi pond includes a pond heater, UV clarifier, and pond lights.

9. Fill The Pond With Water

You can use a garden hose or water pump to do this. If using a hose, be sure to attach it to a water source that is higher than the pond. This is so that the water will flow downhill into the pond. If using municipal water, add a dechlorinator to the water or wait 24 hours for the chlorine to dissipate before adding any koi fish.

10. Add Plants And Other Biological Filtration

Beautiful floating pond flower

One of the most important aspects of how to build a koi pond is filtration, and there are several different ways to achieve it.

Plants: One option is to use plants, which act as natural filters. Use a mixture of floating, emergent, and submerged plants to help oxygenate the water, trap waste materials, and provide shelter for your koi fish.

Rocks and gravel: Rocks and gravel can also function as biological filtration. Besides their aesthetic value, gravel and rocks can be a home to beneficial bacteria. They help break down fish waste and other organic material.

Other animals: Other animals, such as frogs and snails, can also provide biological filtration. However, you typically won’t need to add these creatures since they will naturally be drawn to the water in your backyard oasis.

11. Add Koi Fish

Closeup of koi fish in pond

Now it’s the time during how to build a koi pond to start adding koi! When adding new fish to a pond, it’s important to do so slowly and carefully so they can acclimate to the water temperature. Start by placing the koi fish inside plastic bags with water in them. Slowly acclimate the pond fish by floating their sealed bag in the water for 30 minutes before releasing them into the pond.

12. Clean Up And Finishing Touches

The final step is to do clean up and finishing touches. This includes trimming any plants that are too close to the edge of the pond, as well as removing any stones or debris that may have fallen in during construction.

Grass Roots Pond & Garden Can Help Build Your Koi Pond

Now that you know all the necessary steps for building a koi pond, it’s time to get started on your own backyard oasis. As with any home improvement project, be sure to do your research and consult local experts before getting started.

If you need help building your perfect backyard oasis, our team can help! Just fill out our contact form, and we’ll get the ball rolling.