How to Build a Raised Pond

Key Takeaways

• Location is everything: Choose a spot with 4-6 hours of sunlight daily to balance plant growth and prevent algae blooms.
• Level the ground first: A completely level foundation is the most critical step; you’ll be able to see any slope clearly when the water goes in.
• Stagger your sleepers: For maximum structural integrity, overlap your timber sleepers exactly like you would when laying brickwork.
• Protect the liner: Remove all sharp ground stones and use a high-quality pond underlay to prevent EPDM or PVC liner leaks.

A raised pond in your garden is a simple and effective way to attract wildlife and add an extra personal, relaxing element to your garden. 

According to the aquatic experts at Pond Planet, ”a raised pond requires significantly less upkeep than in-ground alternatives and provides built-in safety features for gardens with pets or young children."

This guide is designed to support you in building the best possible raised pond for your garden, with step-by-step instructions and guidance on sleeper and wood design techniques, depending on how you wish to approach your pond’s construction.

Note: While this guide will specifically focus on building your raised pond from sleepers or wood, it is important to note that concrete blocks and bricks are also suitable options. Concrete blocks and bricks will likely maximise longevity. However, sleepers or wood are aesthetically pleasing and much easier to use.

What you’ll need:

In practical terms, ensure you are well equipped with the right tools to make the job easier. You will need: A spade/shovel Tape measure Spirit level Drill Suitable fasteners and brackets

Once construction is complete, you will also need the right pond equipment, including: Pond underlay and liner A pond pump A pond filter Pond UV Clarifier Appropriate pipework for setup.

Step 1: Select a location with 4 to 6 hours of sunlight

Before building your raised pond, it is important to decide the best place to position it. 

• We recommend placing it in an accessible area for maximum enjoyment and easy access when maintenance is required, though this should not be too often!
• Placing it near an outdoor seating area or within view of your kitchen window is always nice, as the view can be enjoyed from various areas of your home or garden.
• A spot that gets around 4–6 hours of sunlight a day is ideal; too much sun causes algae blooms, while too much shade stunts plant growth.

Calculate the volume of your pond so you know exactly how many sleepers you need, as well as the size of the liner and equipment required.

Step 2: Level the ground for the sleeper foundation

A vital part of the building process is ensuring the area of your garden you have selected for your raised pond is level. Even a slight slope will be obvious once the water goes in! 

• To avoid any disruptions to the sturdiness of your pond, place a long piece of wood in the area where you intend to build it and place your spirit level on top. 
• Repeat this process to gauge the length and width of your land to ensure all areas are level.

In any sections where your spirit level bubble isn’t central, use your spade/shovel to even out the ground until everything is level.

Step 3: Check for rocks and roots that could cause punctures

Before laying any pond liner and underlay, you must check for any hazards that could potentially puncture or damage them. This rule also applies if you are constructing an in-ground pond.

If you find any sharp objects, rocks or stones, remove them from the area meticulously to save any disruption to your building process.

Step 4: Position your sleepers

For those opting for sleepers, you must approach this aspect of your raised pond’s construction with precision, as the positioning of the sleepers will determine the dimensions and definition of the pond.

Commonly, sleepers are available in either 100mm x 200mm or 250mm x 125mm cross sections in lengths of 1.2m, 2.4m or 3.6m, making them ideal for a range of raised pond builds. Raised ponds constructed from newly treated sleepers or wooden decking will create a modern, contemporary effect, whilst older sleepers will create a more rustic look.

• Set down your sleepers in a square or rectangular shape, with them at right angles to one another. 
• Once you’re happy with their position, fasten the sleepers with straight or 90-degree angle brackets.
• When your foundation is complete, layer your sleepers with the same approach until you reach your desired height. Make sure to stagger the joints so that each joint is overlapped with the sleeper above for additional strength and support. 
• Do not add the final layer of sleepers yet, as this needs to be fitted once your pond liner has been added.

Of course, the taller you build your raised pond, the more water there will be, which places more outward pressure on the structure. With this in mind, be sure that your sleepers are fastened together securely, are flush against each other, and are built evenly to ensure a sturdy perimeter. It’s also crucial to ensure that no screws or sharp edges are exposed, as they can puncture the liner.

Step 5: Calculate and add your pond liner

Once you are happy with your layered sleepers, it is time to lay down the pond underlay, which should be as smooth as possible, softening any bumps.

Our pond liner calculator is a brilliant tool to ensure efficiency and precision when building your raised pond. Simply enter your maximum pond length, width and depth in metres, and our clever calculator will work out the correct liner size, including overlap.

Step 6: Fill your pond with water

Position the hose into the structure and let the water fill the space, monitoring the water level to prevent overflowing.

Tap water contains chlorine and chloramines that are harmful to fish and biological filter bacteria. Before turning on your pump or adding plants, you must treat the water with a high-quality pond dechlorinator.

Recommended Product: Oase AquaActiv Safe&Care 500ml  Makes tap water safe by removing toxic chlorine within seconds Immediately binds and neutralises dangerous heavy metals like copper, lead or zinc Removes medication residues - Ideal for use after completion of treatment Stabilises the pH value

Step 7: Trim and secure your pond liner

Once your pond is filled with water, the overhanging pond liner will be visible around the edges. 

• Position your last sleepers to make the top frame of your raised pond, fitting it on top of the excess liner.
• When you are sure it is secure, trim away any overhang to give the structure of your pond the last bit of finesse.

Step 8: Install your pond pump and filter

Whether you have used wood, decking or sleepers for your pond, you must install a robust filtration system to keep the water clean and healthy.

Pond Planet has a great selection of pond pumps and filters for you to purchase, including pump and filter kits for extra ease. All our equipment is suitable for raised or koi ponds and will keep your pond’s wild and aquatic life thriving!

Product Recommendation: For a raised pond, a Pressurised Pond Filter or an All-In-One Pond Filter (like those from Oase or Pontec) is ideal because they are compact and easy to hide beside or behind your sleeper frame.

Step 9: Add your finishing touches

Pond plants and fish are the perfect additions to your raised pond, giving it vibrant colours and life. For quiet nights in the garden or days spent soaking up the sun, the trickling sounds created by your fish will help create a perfect, chilled feel.

Troubleshooting Common Raised Pond Issues

How to build a raised pond with wood

If you have made it to this point, knowing you want to build your raised pond with wood, fear not, the process is very similar to that of the sleepers.

1. After choosing the right location and ground for your pond, gather your decking material and cut it to suit your desired pond size. Use a measuring tape for maximum accuracy before hand-sawing the wood to the correct size.
2. Next, use a drill to make 2 holes at the end of each piece of decking to prevent splitting. Insert the screws and fasten the decking strips together using a suitable drill with a screw head.
3. Line the first four boards in a square or rectangular shape to make a frame, using the holes you have created to screw the boards together. Repeat this method, building upwards until you have reached your preferred height.
4. Unlike the sleeper pond, your decking pond will require corner posts to hold the weight of the water and support your structure. Further support posts may also be required depending on the size of the intended structure. Making sure all posts are level is important, as height disparity can cause issues further down the line, such as overspill.
5. When you are happy with your structure, refer to the previous points of the sleeper-building section to perfect your filtration system and finishing touches!

Frequently Asked Questions (FAQs)

Do I need planning permission for an above-ground pond?

In most UK gardens, you do not need planning permission to build a raised garden pond. However, if your property is listed, located in a conservation area, or the pond will be exceptionally large, it is always best to check with your local planning authority.

Do I have to dig down for a raised pond?

No, the beauty of a raised pond is that it sits entirely above ground, requiring very little digging. You only need to dig enough to ensure the foundation layer of dirt is perfectly level.

Will a raised pond freeze in the winter?

Because a raised pond is exposed to the air on all sides, it is more susceptible to freezing than an in-ground pond. To keep your fish safe during winter, use a pond heater or an ice preventer to ensure a breathing hole remains open on the surface so toxic gases can escape.

What is the cheapest way to build a raised pond?

Building your raised pond yourself lets you save significant money thanks to your DIY skills. Paying someone else to construct your garden’s centrepiece would cost money and potentially decrease the chances of personal customisation.

Build the perfect pond with Pond Planet

With its versatile design and endless opportunities for creativity, your raised garden pond is sure to make the perfect outdoor feature. Give your pond an extra personal touch with our range of pond accessories and decor to keep it vibrant and engaging for your fish.

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