Pond TypeDepth RangeIdeal DepthBenefitsPlease Note
Goldfish Pond45-60cm60cmSafe overwintering and reduced algae bloomsDeeper ponds provide better protection in winter
Koi Pond120-150cm150cmStable temperatures and healthy growthDeep ponds provide protection from predators, but extreme depths can cause health issues
Wildlife Pond15-30cm30cmShallow depths are safer for wildlifeCreate gentle slopes for easier access
Planted Pond15-120cmVaries by plant typeSupports a variety of speciesCombine multiple depths for a range of plants
Decorative Pond30-90cmVaries depending on featureSupports fountains and waterfallsKeep shallow for features, and deeper for fish

How deep should a fish pond be?

The minimum depth of your fish pond depends on the species you are planning to keep. It's crucial to plan the size of your pond for the fish you'll be keeping in advance, to make sure you get the correct liner size and pond equipment.

Goldfish pond depth

If you're looking at keeping goldfish or other pond fish, the minimum recommended depth your pond should be is 45cm (18 inches). This allows space for them to escape the freezing surface of the water during winter, resting in a semi-dormant state (similar to hibernation) in the warmer bottom layer of the pond.

For better protection, you could aim for a water depth of 60cm (24 inches). To achieve this depth, you'll likely need to dig or construct the pond to a height of 75cm (30 inches), as ponds aren't typically filled to the very top.

Koi pond depth

Koi carp require far deeper ponds than other fish. The ideal depth is around 120-150cm (4-5 feet), allowing plenty of space for your fish to grow properly and overwinter safely. Some Koi ponds are over 180cm in depth, but extremely deep ponds can increase the risk of your Koi developing swim bladder issues.

Tip: Don't forget that more or larger fish always means more depth and a larger pond. Always meet the minimum size requirements for the amount of fish you have.

Garden pond with fish and plants
The depth of your pond depends on the species you are wanting to keep

How deep should a wildlife pond be?

Wildlife ponds are a lot different to fish ponds, they're best kept shallow and fish free. A maximum depth of 30cm (12 inches) is recommended. Shallow areas of the pond are very important to keep wildlife safe as most creatures thrive in just a few inches of water. Adding planting shelves will help to increase biodiversity.

Tip: Be sure to include gentle, gradual sloping edges to allow frogs, birds, and insects to access and exit the pond safely.

Frog sitting on a lily pad in a wildlife pond
Wildlife ponds are better kept shallow to allow easy access

How deep should a planted pond be?

Different types of pond plants have different planting requirements, thriving at different depths:

  • Moisture-loving plants: ideal for planting in wet soil or damp compost at the edge of your pond, or in a bog zone.
  • Marginal plants: these plants typically require around 15-30cm (6-12 inches) of water, making them ideal for planting on shelves surrounding the edge of your pond.
  • Water lilies: most varieties need around 90-120cm (3-4 feet) of water, so that their leaves can remain submerged, allowing them to be better protected from pests.
  • Oxygenating plants: thrive in deep ponds, with strands able to reach up to 180cm (6 feet)

Tip: For a diverse eco-system, build your pond with varied depths to suit various plant species.

Where should I place my pond pump?

  • During summer: situate your pump at the deepest point of your pond for debris removal. This is especially ideal for solids-handling filter pumps.
  • During winter: move the pump to a shallow shelf, or turn it off during cold months to leave fish undisturbed in warmer bottom layers, and avoid circulating cold water to the bottom.
  • For fountain pumps: if your pond is too deep for a fountain pump, you can raise it using a planting basket, or choose a floating fountain pump.

Ready to choose your pond pump? Check out our high quality selection.

Are deeper ponds better?

There are many pros and cons when it comes to building a deeper pond that are worth considering:

Pros:

  • Provides better protection for overwintering fish
  • Reduces algae growth thanks to less sunlight reaching the bottom
  • Warms and cools at a slower rate, for better thermal stability
  • Provides more room for a variety of plants

Cons:

  • Potential issues for wildlife and shallow-growing plants
  • Can be too deep for some fountain features
  • Potential to delay seasonal temperature changes

Ultimately, the choice of how deep you should build your pond depends entirely on how you plan to stock, decorate, plant, and maintain it.

Koi fish swimming next to water lilies in a pond
Deeper ponds are best for Koi fish and water lilies

Pond depth guide

Depth (cm)Depth (Inches)Best suited for
00Moisture-loving plants
156Marginal plants
3012Wildlife ponds
6024Goldfish ponds
9036Water lilies
12048Koi ponds

Ready to build your pond?

The planning stage is very important in constructing a successful pond. Once you've settled on the dimensions of your pond, you're ready to get started.

For a step-by-step guide on building your own pond, check out our handy guide here.

Need help choosing a pond filter or pump? Check out our guides: