We in the Pacific Northwest love our water. You will often find us on or near water – kayaking, paddleboarding, swimming, or fishing. Backyard koi ponds are a great way to bring beauty and enjoyment to your outdoor living space. Whether you’re looking for an elegant focal point for your garden or a peaceful refuge from the hustle and bustle of everyday life, a koi water garden provides a unique opportunity to connect with nature.

What are Koi Ponds?

Koi ponds are designed to house koi fish, a type of ornamental carp that has been bred for colorful patterns. In addition to the elegant beauty of these fish, they’re an ideal choice for creating a tranquil environment in your backyard or garden. There are special requirements for a koi pond. It needs to be deep enough for the pond fish to survive and there has to be a sufficient filtration system in place to ensure that the pond is kept clean.

Koi fish

What are Koi Fish?

Koi fish are an ornamental breed of carp that have been prized for centuries for their unique patterns and colors. They come in a variety of sizes and can live up to 30 years if properly cared for. The largest recorded koi was 66 cm long! Koi fish are capable of growing throughout their entire lifetime and larger and older fish, which are more visually stunning, can sell for thousands of dollars.

Are Koi Ponds Landscape Features?

Koi ponds are not only beautiful additions to any landscape, but they also serve as a habitat for wildlife and fish. Koi ponds, along with other water features, make excellent focal in the garden, providing hours of entertainment and relaxation. With proper care and maintenance, koi ponds can remain thriving ecosystems for plants and fish for years to come.

Types of Koi Ponds

landcaped backyard with large waterfall and pond
landscaped backyard with a large waterfall and pond

There are a variety of different koi ponds that can be installed in your backyard. Waterfalls and koi ponds are a natural blend of relaxation that provides healthy negative ions for you and aeration for your fish. Minimalist concrete ponds can be built above ground or below and can be a basic rectangle shape. Sitting areas with firepits around a koi pond is a fantastic way to entertain or relax without ever leaving your home. Asian landscapes are a natural fit with a koi water garden and become a peaceful oasis for both animals and people.

Each type of backyard koi pond has its own set of advantages and disadvantages so it’s important to choose the one that best suits your needs before you start.

Ideal Depth of a Koi Pond

The ideal depth for a backyard koi pond is generally between four and six feet. The deeper the pond, the more room there will be for the fish to swim and explore. This greater water volume also helps stabilize temperatures, allowing your koi to be comfortable throughout the year. Furthermore, when looking at the ratios between the length and width of the pond and surface area, a deeper pond is often recommended for larger ponds with more koi.

Steps to Building a Koi Pond

Building a koi pond can seem like an overwhelming task, but with the proper planning and preparation, it is relatively simple. Here is a general overview of how to build a koi pond:

  • Planning
  • Excavation
  • Lining
  • Filtration and plumbing
  • Water and Plants
  • Introduce Koi


Before beginning construction of your koi pond, it’s essential to plan out the shape, size, and location of the pond. Consider the amount of space you have available, the amount of sunlight your pond will receive, and the topography of the site. It’s best to locate the pond where it will receive at least four to six hours of direct sunlight to provide an ideal environment for the koi to thrive.


Once you have a plan in place, it’s time to begin excavating the area where the pond will be located. The depth and size of the pond will depend on the number and size of the koi you plan to raise. Generally, koi ponds are between three and six feet deep, and their surface area is at least ten times the length of the koi, allowing the fish plenty of space to swim.


After excavation, it’s time to install the pond liner, which is typically made of a flexible and durable material such as EPDM rubber or PVC. The liner is usually laid over a bed of sand or a geotextile fabric then gravel and rocks are added to create a natural place for koi to live.

Filtration and Plumbing

Once the liner is in place, it’s time to install the filtration system and plumbing. Filtration is essential for keeping the water clean and healthy for the koi. A typical koi pond filtration system includes a skimmer to remove debris, a biological filter to remove toxins, and a mechanical filter to trap solids. Plumbing is used to connect the filtration system, a pump, and any other water features such as waterfalls or fountains.

Water and Plants

After the filtration system is installed, it’s time to fill the pond with water. It’s important to allow the water to sit for several days to allow chemicals to evaporate and the temperature to stabilize before introducing the fish. Adding native plants around the perimeter of the pond can help to create a natural and attractive environment.

Introduce Koi

Once the water temperature has stabilized, it’s time to introduce the koi to their new home. Start with a small number of pond fish and monitor the water quality closely. Proper feeding, water changing, and overall care are essential for the health and growth of the fish.

How Much Maintenance Do Koi Ponds Require?

Koi ponds require regular maintenance to keep them healthy and thriving. Regular water changes are necessary to reduce the buildup of ammonia, nitrites, and other toxins that can be dangerous for pond fish. Depending on the size of your pond and the number of koi, it’s recommended to do a partial water change of 10-15% once or twice a month. Additionally, it’s important to clean and maintain the filtration system, as this is essential for keeping the water clean. It’s also advisable to check the pH level of the pond periodically to make sure that it remains within an acceptable range for koi (6.5-8.0).

Where can I Install a Koi Pond?

Koi ponds can be installed almost anywhere, as long as they receive adequate sunlight and the conditions are suitable for the fish. It’s important to ensure that the pond is not located near any hazardous materials or substances that could contaminate it, such as fertilizers, pesticides, or chemicals. Additionally, it’s best to avoid installing a koi pond in an area prone to flooding or high winds.

water feature flowing into large pond by Greenhaven Landscapes
Large pond with waterfall, patio, and firepit

Choosing Fish and Aquatic Plants for Your Backyard Pond

Once you have your koi pond installed, it’s time to select the fish and aquatic plants that will inhabit it. When choosing koi look for ones with bright colors and unique patterns. It’s also important to check whether or not they are compatible with other species of fish in your pond. For aquatic plants, there is a wide variety of options to choose from, including floating plants, submerged plants, and marginal plants. It’s important to select the right plants for your koi pond so that they can thrive in the pond.

Choosing the Location Of Your Pond

When selecting a location for your koi pond, it’s important to consider factors such as sunlight, shade, and shelter from the wind. Additionally, if you’re planning to install a waterfall or other water feature, make sure that it will not be obstructed by trees or buildings so it can be seen. Any water feature you add to your yard should be visually interesting and provide a place for your family and friends to relax. Water gardens and ponds can be great conversation starters and provide a place to entertain so ensure that your landscape design is well thought out.

Is it a Good Idea to Have a Koi Pond?

Overall, with the proper care and maintenance, koi ponds can be a beautiful and rewarding addition to any outdoor space. With the right set-up and knowledge of how to care for them, you can enjoy your own backyard oasis filled with colorful koi that will provide years of enjoyment for you and your family.

Koi Pond Construction in Portland

There is nothing like sitting by a pond, watching the water move, and feeling the tension drain away while you watch your fish. Koi ponds are a great way to bring beauty and tranquility to your outdoor space. Not only are they visually stunning, but they also provide an opportunity to connect with nature in a truly unique way.

Greenhaven Landscapes has been building and maintaining ponds and water features in the Portland area for over 25 years. We will work with you to design the perfect pond or water feature for your backyard that you can enjoy for years. Call us today to get started.