How To Build a Koi Pond

Sean Perry, DVM
By Sean Perry, DVM on May 31, 2023
Koi pond

In This Article


What Is a Koi Pond?

Koi fish are commonly kept as ornamental fish in outdoor ponds or garden water features. They have a rich history in Asian culture dating back thousands of years. Their bright vibrant scales and lively swimming behaviors can provide a splash of color and activity to any outdoor pond.

What Do You Need for a Koi Pond?

  • Pond liner

  • Pond skimmer

  • Pond filter

  • External pump with pump basket

  • UV clarifier

  • Drains

  • Aeration equipment

  • Automatic top off

  • Drains

  • PVC primer and glue

  • Silicone

  • Minimum depth of three feet

Where Should You Place Your Koi Pond?

Koi ponds are typically built outside; however, they can also be built into a home. Any koi pond constructed indoors should be planned with the construction of a house or during renovations.

Outdoor koi ponds should not be in direct sunlight and should receive about four hours of sunlight per day. The pond should not be near any trees to limit debris falling into the pond.  Additionally, the location in which you place your koi pond should be able to withstand the weight of the water used in the pond and not impact any infrastructure.

Water for Koi Ponds

Water can be stored in a water container that can then be used to add water to the koi pond after water evaporates. This can be set on an automatic filler or can be filled manually. Rainwater can be collected in a barrel, or you can use treated tap water. Do not use tap water for a koi pond without conditioning the water. Tap water may contain low levels of chlorine to help maintain drinking water standards, but these levels are toxic to fish.

Koi ponds require a significant amount of equipment to function due to the large volume of water. This includes pond filter, aerator, external pump with pump basket, UV Clarifier, and water heater (for cold environments during winter). Having a water quality kit at home is vital to ensure you can provide good quality water for your koi pond.

Decorating Your Koi Pond

Koi ponds traditionally do not incorporate many decorations or substrate into the pond. However, water garden ponds are an alternative to koi ponds—these gardens are heavily planted ponds that typically have substrate such as pea gravel. Rocks and other plants like water lilies can be used to aquascape water gardens. 

How To Set Up Your Koi Pond

Many homeowners are capable of DIY koi pond construction, but it’s recommended you consult with a professional builder or someone who has experience building aquatic systems before taking on the project. It’s important to plan out your koi pond to include mechanical, biological, and other filtration types.

First, determine how many animals you want in your koi pond and choose the correct components to build it. If you intend to breed your koi fish, a larger pond is necessary. When you determine the type of filtration you will use and the size of the pond, you can select the size of the filtration.

It’s important to overestimate the total volume needed for filtration. This gives you a buffer with your pond in case regular maintenance won’t happen on a regular schedule. Water turnover should be high in a koi pond with a large amount of mechanical filtration. The total volume of the system should pass through the filtration every 2–4 hours.

Koi Pond Safety Measures

Predator deterrents that are used for koi ponds include:

  • Fake alligator heads

  • Fake birds of prey (owls)

  • Protective netting

  • Floating plants for koi to hide in

  • Ultrasonic and sonic deterrent devices

Koi ponds can attract predators due to the constant water source and the koi themselves–since they are a food item. These include:

  • Birds (herons and other aquatic birds)

  • Racoons

  • Coyotes

  • Foxes

  • Domestic cats

Normal pest control methods should be taken to deter these animals from becoming a nuisance or predators to the koi. Sometimes you can place translucent fishing line across the pond to prevent birds from diving into the koi pond. If you have a cat in the house, make sure to supervise them if they are allowed outside near the pond area.

Koi ponds may also be set up in a environment for other species to live. Some koi-friendly animals that can cohabitate with koi fish include:

Koi Pond FAQs

Are koi ponds hard to maintain?

When built appropriately with the correct filtration system, koi ponds are not difficult to maintain. A well-maintained koi pond may only need 30 minutes of care per week.

Is it a good idea to have a koi pond?

Koi ponds require a significant financial investment to be built properly. However, they can be rewarding and are low maintenance after the initial set up.

How much does it cost to put in a koi pond?

Installing a koi pond can be expensive depending on how it is designed, and the filtration used. Costs can range from a few thousand dollars to tens of thousands of dollars.

How deep do koi ponds need to be?

Koi ponds should be at least three feet deep or more depending on the number of animals and size of the pond.

Featured Image: Stickney

Sean Perry, DVM


Sean Perry, DVM


Dr. Sean Perry completed his undergraduate degree at the University of California, Santa Cruz, earning a Bachelor of Science in...

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