Designing a pond

How to get the design and planning stage right first time.

Building ponds

Where, how and what materials and equipment. The hard work bit.

Koi Pond Pumps

How to choose and where to buy your koi pond pump.

Koi Pond Filters

Selecting the correct filter for your koi pond.

Koi Pond Food

Choosing the right food to keep your koi fit and healthy.

Designing Your Koi Pond and Garden

Perfect Planning Prevents Piss Poor Presentation.

Koi pond design has to be the most important aspect of the pond building cycle. Get this wrong and you have not only wasted a lot of time and maybe money, but you may be left with a koi pond which is not suitable for keeping koi in at all.

Get it right however, and you should end up with a thing of beauty which will give you years of pleasure and provide the perfect home for your new fish.

Location, Location, Location

Koi PictureThe first and one of the most important things to consider is location. This is partly down to personal preference. Some people like a pond to be near to the house for viewing from indoors, while others prefer it to be a separate entity which they can visit when the mood takes them. Remember however, a pond is difficult to move once installed.

It should be in a place where it can be enjoyed all year round. Too far from the house and feeding and maintenance can become a chore and missed out during bad weather. Too near to the house or walls can cause problems with deep excavations interfering with foundations.

Remember to consider the safety of pets and young children. Remember a child can drown in water only a few inches deep. If you have young children then maybe a koi pond should wait until they are older and build a pebble filled water feature for now.

Try to position the pond so it is sheltered from cold winds and receives sunlight for at least half the day. Where possible avoid siting your pond under or too near to overhanging deciduous trees, as their leaves and blossom will fall into the pond and become a major headache in the autumn and winter months unless you are prepared to net the pond daily. Bear in mind that the leaves of willow, elder, oak, yew, poplars and laburnums trees are highly toxic. Additionally this will avoid tree roots piercing pond liners or cracking concrete.

Also avoid areas where surface water tends to collect, or areas with a high water table as this could push up under the pond liner or structure and create problems. Also avoiding these areas will reduce the risk of any pollutants being washed into the pond during heavy rain.

Another thing to consider is how you are going to carry out the excavations. Gaining access for a mini digger and removing excavated soil should be thought about before it is too late.

Power and water supply and drainage need to be considered. Armoured cable isn't cheap and nor is the laying of permanent water drainage. Try to find the house plans if you can and see where all existing water pipes, gas pipes and other service supplies are located. You don't want to find them the hard way after you start digging.

Size matters, but so does shape and depth


Size should be in proportion to the surroundings, and do consider that if a pond is too wide, it is very difficult to catch the fish even with a long purpose built koi net. I would suggest not wider that 12ft and no longer than about 20ft. Ideally it should be at least five feet deep, preferably six feet deep. This is particularly important if you do not live in the South of England as deeper water does remain slightly warmer in very cold weather.

Remember, the bigger the pond, the more fish you can keep, but you will need a bigger and more expensive filtration system. Also any water treatments required are in proportion to the number of gallons of water in the pond and filter system.


The shape and surface area are generally down to personal preferences but it is always best to create a shape which allows for a flow of water between the outlet, bottom drain or pump and the inflow. This will allow solid waste to be circulated and removed to the  filter and not get caught in nooks and crannies. Using complex shapes is also best avoided to alleviate construction difficulties and create less folds in pond liners.


Ideally koi need a depth of at least 4 feet in the deepest part of the pond to allow over wintering successfully. This will reduce the likelihood of temperature fluctuations which can encourage algae growth and be harmful to fish health. Koi also appreciate the exercise of being able to dive to these greater depths. It is helpful in maintaining a healthy and balanced pond to have at least 40% of the pond area at this maximum depth.

The easiest way to envisage you pond in situ is to take a rope or hose and lay it where you think it will be sited. It is much easier to see how the finished pond will look using this method and once you are happy with your design, the pond outline can be marked out.

Don’t forget to allow for any streams or waterfall features you are considering and allow for planting areas. Normally a shelf is allowed for around the edge of a pond, but in the case of koi, who can be particularly destructive towards plants, it is sometimes best to allow a separate area for planting or even a separate adjacent pond.


There are various styles of pond such as formal and informal, sunken or raised, and this decision is down mainly to personal preference. If you are at all worried about small children around a deep koi pond, then a raised pond can sometimes be a safer option particularly as it is then easier to cover with strong mesh to avoid accidents. Formal ponds are usually square, oblong or exact circles, the type often seen in stately homes, whereas informal ponds are more often kidney or irregular shapes and lend themselves more to a natural cottage garden look.

Construction Method

Whatever style you choose, do consider which construction techniques you are using and remember that a liner will create many creases in a square or rectangular shaped pond. If you do want to use a square liner, maybe consider having a special box liner made up to order.

On the other hand, concrete block work and concreting are easier in a square or oblong shape.

Materials – Rendered Brick, Fibreglass, Concrete or Liner

OK, so you’ve got your location and design mapped out. The next thing to consider is how to line your pond. There are several different ways of lining the pond. You can use a flexible liner, made out of pvc or butyl rubber. Alternatively, you can build the pond out of brick. If you choose the brick option then you will also have to render & seal the brick work to retain the water with products such as G4 pond sealer, or fibreglass.

Consider whether you are intending to install bottom drains. If so, provision must be made in the construction for this purpose. Bottom drains are available for both concrete and liner ponds. Also protein skimmers should be considered before going ahead with your final decision on construction methods. Again, these are available for both concrete and liners. Although they can be added to a liner pond at a later date, it is easier to plan this from the beginning. More on all of this in our equipment pages.

So that's about it for the design considerations. You are almost ready to start thinking about the building of your koi pond. You know how you want it to look, where it is going to go and with which materials you are going to build it.

Our next section deals with choosing koi pond equipment such as pumps, filters and UV clarifiers, or if you already know what you want to install in the way of hardware, you can move straight on to the pond building section.

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