Building a garden pond

Building a Garden Pond

Good planning is essential prior to building a pond. It can save you both time and money. Therefore take time to research all considerations before designing and building your beautiful and functional garden fish pond.

Building a Koi Fish Pond doesn’t have to be overwhelming or complicated once you have the correct pond construction information at your fingertips. Why not check out the Build an easy Koi Fish Pond! Guide.

The positioning of the pond, type, space, size and depth are the fundamental requirements to consider initially. Ensure it is in proportion with the overall size of the garden, complimenting it and not over dominating it. The size of your pond and population of fish in it, will determine how big they will grow eventually.

There are two types of ponds – Either a pond with liner or a pre-formed pond ideally made from fibreglass. If you intend to keep Koi you must use a pond liner as the depth required needs to be a minimum of 1.5 metres.

If you require a pond with a volume in excess of 500 litres of water then it is advisable and more economical to use a pond liner.

Where to position the pond, consider the following:-

  • The view from the house.

  • Electricity supply to the pond for the pump. The pond will need to be positioned close to the house, unless you have an external power supply.

  • Make sure there are no underground utilities. Check with your local utility company if needed.

  • Do not position too near a tree that may result in its leaves falling into the pond or its roots causing damage to your pond liner.

  • Most aquatic plants need between 4 and 6 hours of sunlight a day to ensure healthy growth, however excessive sunshine may result in over growth of blanket weed.

  • Ensure your pond is not positioned at the bottom of a slope, as rain water will run into the pond, which may contain chemicals from your garden which could be harmful to your garden fish.


  1. What type of pond to build.
    Preformed ponds
    Preformed ponds are available in a variety of shapes and depths, usually with plant shelves built in. They are ideal for novice pond builders as they are hard wearing and less likely to puncture than a pond liner and are easier to install.
    Pond liners
    Pond liners are cheaper to buy and give more creativity as they are very flexible and are designed to conform to any hole regardless of its shape

    To calculate the amount of pond liner you need for the size of your pond you need to measure:-

    Length = length of pond + (2 x maximum depth) + 1m edging
    Width = width of pond + (2 x maximum depth) + 1m edging

  2. Installation
    Marking out the pond at its intended location is the first thing to do. In order to do this, you need to define the perimeter of the pond using either string, a length of hosepipe, sand or something similar. Next, you need to excavate the area down to the depth of the first shelf. Mark out the outline of the shelf and then proceed to dig out the centre of the pond, adding additional shelves if required, until the depth has been reached. The next stage is to place the liner inside the pond, firstly removing any sharp stones. Before the lining is placed into the hole, spread a layer of soft sand over the area which will protect the liner being punctured. For further protection you may like to add pond underlay. Spread the pond liner over the hole and secure the sides using bricks. Try to leave a 12cm overlap of the pond liner around the edges of the pond.
  3. Decoration
    Edge your pond with rocks, boulders, plants or even turf.
  4. Plants
    Add and pot up your plants, remembering if you intend to keep Koi, who love to eat some varieties of plants, you should protect them by using gravel on top of the soil after planting them in their containers.
  5. Install the pump, filter and UV clarifier.
  6. Add water
    Use tap water to fill your garden pond.
  7. Add garden fish.
    It is advisable to wait at least six weeks after adding, testing the water and allowing the plant life to settle before adding your fish and also to allow friendly bacteria to develop.

  8. Consider any safety issues
    Children under the age of five are at most risk of drowning in garden fish ponds, so if you have children or grandchildren, it is a good idea to install a rigid steel mesh frame over the fish pond. It should be secured firmly and able to withstand the weight of a small child. The mesh should be positioned above the water level.

Once you have built your beautiful functional garden fish pond and have placed your fish in it, why not check out the section on how to care for garden fish.