Beginners guide: How to build a garden pond
Garden ponds are a great addition to your garden.
They look great, add sensory experience to your garden, encourage wildlife, and can make a smaller garden look bigger.
According to Defra, 70% of garden ponds have been lost since the 19th century, and a small garden pond could be a great way to reintroduce them to our outdoor spaces.
This will help habitats and boost biodiversity in your garden, and this in turn will help you to deal with garden pests in your home.
Here, we answer some of the most common questions about garden ponds to help you to get started.
Can you just dig a hole to make a pond?
While this would be a nice, easy option, you unfortunately can’t just dig a hole in the ground to make a pond.
Building a pond is a complicated task.
There are lots of considerations, including violating pond regulations if you build a pond in the wrong place, potentially damaging wildlife habitats.
Be mindful of electric and water lines
It’s worth noting that electric and water lines go from place to place under the surface.
You could end up damaging these lines if you don’t research the area first.
Digging soil is a difficult job anyway, but made even worse if you discover after digging that there is an electric or water line underground.
Keep in mind though that you need to still be close to water lines still as you’ll need easy access to water.
Damaging wildlife
Some soil can’t be used to build a pond as they have limited capacity to hold water.
If you accidentally build a garden pond on those soils, they could cause damage to any plants and wildlife nearby. These could be irreversible.
As mentioned, a pond built in the right place will attract wildlife and boost biodiversity in your garden.
Absorbing water
If you just dig a hole in the ground and pour water in, it won’t be a pond.
After a while the water will absorb into the ground – to stop this happening you need to put pond liners into your pond.
We’ll talk more about pond liners later, but it’s worth noting the best kind are made of rubber as these are low maintenance and budget-friendly. These prevent water soaking into the soil.
Not having the right depth
Depth is an underrated part of a pond, but it’s crucial.
If a pond is too shallow, it will get hot really quickly and can then be harmful to the fish living in it. The oxygen levels can then be too low, too.
Alongside overheating, ponds that are too shallow will also freeze as fast in the winter as they overheat in the summer.
Frozen water will also kill your fish if the heat doesn’t.
Another issue with a pond that is too shallow is that predators will find it easier to get to fish in a shallow pond.
However, if the pond is too deep, maintenance can be really tricky. Algae will have too much toom to grow, which can be harmful for the ecosystem of the pond.
The key is for the depth to be perfectly balanced.
Size matters
If your pond is too small, it can also be detrimental to the fish and plant life that live in it. It can become too cramped too quickly, and then be difficult to maintain.
A pond that is too large will also have issues, it will be hard to look after and you also have the risk of an overflow if we get too much rain.
Insurance
Building a pond in your own home doesn’t mean you’re exempt from legal restrictions.
Your insurance could go up and sometimes, insurance won’t even cover the new pond.
It’s important to look into this before going ahead and building one.
What should you put in the bottom of a small pond?
As mentioned previously, you’ll need a liner at the bottom of your pond, but you can put things on top of that to make it more aesthetically pleasing. Here, we explore some of the options.
Bare bottom
Simply having the liner at the bottom of a pond is fine.
It’s easy to clean, allowing you to quickly spot and remove debris and waste.
However, a bare bottom pond provides no surface for any good bacteria to linger.
These bacteria are important as they can help to break down fish waste and other nutrients.
It also offers no protection from UV rays which can degrade the liner over time.
Sand
If you want an authentic, natural look for your pond then sand could be the way to go.
It’s also pleasant to walk on if you have a wading pond.
However, it can easily shift and settle so might need to be raked to prevent it building up into one area.
Sand particles can also clog your pump and filter, and offers minimal space for helpful bacteria to grow.
Like a bare bottom pond, a sand lined pond will also provide little UV protection, unless you apply a special coating.
Pea gravel
Smooth pea gravel can make for a very attractive pond bottom.
The small stones won’t obstruct your water flow, but they’re also large enough not to impact your pump or filter like sand will.
It also settles easily, and is easy to clean up if needed. Using the right amount will provide a stable pond base as well as the perfect setting for bacterial habitats.
River rock
For a natural appearance in your pond, small rounded river rocks can be a good option.
Gaps between the stones will allow water flow, but the clean up operation will be harder than with pea gravel.
Use a thicker layer for more stability, as smaller river rock may be drawn into your pump.
Opting for larger river rocks will stay better, although again hard to keep clean by vacuuming.
Using rounder rocks will prevent damage to your pond liner.
Bentonite clay
This contains montmorillonite which absorbs nutrients, chemicals and waste from your pond water.
It will also provide a natural liner sealant.
As well as having a high cation exchange capacity which will attract and hold positively charged ions, therefore helping to remove ammonia, heavy metals and other contaminants from your pond.
Pond soiling mix
Some ponds use soil, potting mix or compost to create a more natural environment.
However, this can lead to large amounts of debris, creating sediments which lack oxygen.
This can in turn harm your fish.
If you opt for this base, be sure to regularly stir your pond to prevent this from happening.
Does a pond need a pump? Will goldfish survive without one?
Yes, a pond will need a pump – especially if you plan to have fish inside.
A pump will keep the water flowing in your pond, as well as keep it properly oxygenated and clean of algae and any unwanted bacteria.
Koi and goldfish will also need a pump to survive in your pond.
How can you make a pond hold water naturally without a liner?
As mentioned, it is generally recommended to have a pond liner to help with water absorption.
However, it is possible to build a pond that holds water without a liner.
First of all, you need to understand soil and water flow.
If a pond doesn’t naturally retain water, it is usually because of the soil type, location of the pond, or poor construction practices.
If you can address these factors, you can turn your pond into a durable water reservoir that holds water for long periods.
Not all soil types will hold water, so assessing the ones that will is crucial.
Clay soil
This is best for holding water due to its small particles and tight structure. It doesn’t allow water to pass through it easily.
Sandy soil
This is not ideal for ponds, as it allows water to seep away quickly. Sand has large particles with spaces between them.
Loam soil
This contains a mix of clay, silt and sand – it’s ideal for gardening but can vary in water holding capacity.
How to check your soil type
A simple test to check what soil type you have where you want your pond to be is by picking up a handful of damp soil.
Squeeze it tightly, if it crumbles it’s likely you have sandy soil. If it forms a sticky clump, you may have clay which is ideal for ponds.
Another way to check is to fill a jar with soil and water, shake it well and let it settle.
Sandy soil will settle at the bottom, while clay will go on top.
Natural methods to seal a pond
Compacting the soil
Once you have determined that the soil has enough clay in it, compacting it can make it nearly waterproof.
Use a heavy roller or your feet to pack the soil tightly.
A compacted layer reduces water movement by eliminating spaces where any water might leak out.
Adding Bentonite Clay
If natural clay within the soil is low, this can help enhance the chances of water retention.
Bentonite is natural and swells when wet, therefore filling gaps and reducing leakage.
Spread a layer of it over the pond bottom and sides, then compact it.
It’s highly effective and often used as a natural pond sealer.
Using animal activity
Livestock can aid in compacting soil.
Allowing animals to walk over the pond area can help to press the soil down, creating a compact, watertight layer.
However, this is less controlled and can take time to be effective.
Also, most of us don’t have a herd of cows nearby we can call on! Assuming dogs or cats might have a similar impact?
Soil cement mixer
For small ponds, mixing a little cement with your soil can improve the water retention.
A 5-10% cement to soil ratio will create a surface that prevents leaks.
After applying the mixture, pack it down well – combining natural and minimal material to get the best results.
Lining the pond with clay
Using clay as a liner is one of the oldest and most natural ways to line a pond.
It’s effective, because it swells when wet, closing off any gaps where water might escape.
It’s durable, long-lasting whilst also being eco-friendly and natural.
It also requires minimal maintenance once installed so it’s a win for everyone.
Is a pond better in sun or shade?
It is genuinely recommended to have a pond in the shade, however it needs to be exposed to some sunlight in order to benefit any aquatic plant life and fish that live inside.
A shady pond space is best as it helps to keep your fish hidden from predators, whilst maintaining a cooler water temperature for them.
How deep should a garden pond be?
As already suggested, there are perils to having a garden pond that is too shallow, but equally having one too deep. As Goldilocks said, the key is getting it ‘just right’.
The recommended depth of a garden pond is between two and six feet, or between 61-183cm.
This depth provides a good amount of space for plants to grow, without getting out of control and reducing oxygen levels.
It also allows for water circulation which is important for maintaining a good quality of water for the animals and plants within.
READ MORE: