How To Build A Pond: A Step-By-Step Guide

Choosing a pond type

Before getting started on the build, you'll need to decide whether you would prefer a wildlife pond or a large pond for fish. This choice is important during the planning stage, as it affects the size, depth, location, and filtration requirements.

Wildlife ponds

Wildlife ponds are excellent for smaller gardens, and provide a natural aesthetic. Although they are kept fishless, they attract frogs, birds, insects, and newts, perfect for wildlife lovers. They are just as customisable as fish ponds, typically with less maintenance requirements, and usually featuring native plants and gentle inclines. They also boost biodiversity and have minimal costs or intervention once they are established.

Fish ponds

If you'd like to keep Koi, Goldfish, or other fish, you'll need a larger and deeper pond. They are a great choice for larger gardens, and provide far more room for different plant varieties, some even featuring waterfalls or fountain features. Although they require a lot more planning, these ponds are a relaxing focal point for your garden year round.

Picking a location

The right placement is important. You may want to sketch a rough design of your garden layout, considering environmental factors before you get started.

Things to consider:

• Sunlight: areas that receive high levels of sunlight during the day, such as South-facing sections, come with benefits as well as disadvantages. Your aquatic plants will thrive in more direct sunlight, but unfortunately algae will too. With regular maintenance, treatment, and a UV clarifier, this can be combatted.
• Trees: although trees are great at reducing algae growth by providing shade, there are a few issues that could become apparent in the future. Root growth from beneath the liner has the potential to cause damage, and leaves falling into the water can quickly decay, affecting your clarity and water quality. If you do choose to situate your pond close to a tree, be sure to scoop out fallen leaves with a net regularly.
• Power outlets: fish ponds, and some wildlife ponds, often require pumps and filtration. You will need to situate it close enough that your equipment can reach an outlet.

If you're building an in-ground pond, it is generally recommended to stay away from large tree roots, and to build it at least two metres away from any buildings. Being mindful of access to your pond throughout the seasons can save a lot of hassle come autumn and winter time.

Deciding on measurements

After you've decided on a location, you will need to plan the size and shape. You may think your pond is large enough whilst you're digging, but once it's full of water and fully planted and decorated, it may seem a lot smaller. If you're unsure, size up. The useable water space may even be reduced when adding edging materials and decorations, so it's always better to build it on the larger side.

You may want to consider using an old Belfast sink or bathtub for a wildlife pond, as you don't need to meet any minimum size requirements. Even small ponds can attract wildlife with the right planting. For more simple and budget-friendly ideas, check out our guide here.

For fish ponds, you will need to meet a minimum size requirement for it to be safe and comfortable for your fish. The size and volume depends on the species you are planning to keep, so it's important to research this in advance. Too small, and fish can become stressed, affecting their health severely. 

Tip: For Koi fish, your pond needs to be at least 3 feet deep. Try our Volume Calculator to work out the suitable equipment you'll need for the measurements you choose.

Starting the build

There are two main methods for building a pond, in-ground or raised. Each option has it's own benefits, it just comes down to space, tools, and the aesthetic you prefer.

In-ground:

• Brings a more natural feel
• Easier for wildlife to access
• More flexible for planting and decorating
• No additional materials required, just a liner and underlay

Raised:

• Can be styled to suit your garden
• Can be disassembled and rebuilt if you move house
• Perfect for gardens where digging is not possible
• Faster and cleaner to construct

Most of the steps are the same for building both types, except for the initial digging/constructing.

Digging an in-ground pond

Start by planning out a shape using a length of rope or a hose. Begin to dig down, leaving a shallow shelf around the edge for plants and wildlife. Create multiple depths, including a deeper section in the centre. Varying depths not only add a better visual appeal, but also helps with temperature regulation, and supports diverse plant and animal life. If you're hoping to attract wildlife, create a gentle slope on the side for creatures to enter and exit the water with ease.

Building an elevated pond

Raised ponds are a great solution if digging isn't possible, or if you may move house in the future. You can build a solid frame using timber sleepers easily, or even use a pre-built pond or existing vessel that will withstand water pressure, such as a Belfast sink or bathtub. These ponds are perfect for patios or small gardens. You can even style it to achieve a modern feel using the right materials.

For more advice, check out our help guide on building a raised pond.

Lining and filling your pond

Once your shape is ready, you'll want to remove any sharp stones, roots, or debris that may cause a puncture to the pond liner. 

1. Lay an underlay to protect your liner, covering the entire base and walls.
2. Cut and position your liner, making sure to leave enough overlap at the edges for anchoring.
3. Fill the pond with water slowly, adjusting the liner as it fills to reduce creases and create neat folds where needed.
4. Add a water dechlorinator to remove any harmful chemicals found in tap water before planting or adding fish.

Installing your liner correctly protects your pond from leaks, and improves the visual finish. Once your pond is filled, be sure to secure the edges of the liner using stones, slabs, or edging trim. 

Use our liner size calculator before purchasing your liner to make sure you have the right size for your measurements.

Need more help? Try reading our help guide How To Install Your New Pond Liner for more tips and advice, as well as step-by-step instructions.

Plants and equipment

After lining and filling with water, you'll want to bring it to life with live plants. This setup differs based on taste and the kind of pond you're building. Aquatic plants help to reduce algae, and provide shelter for fish and wildlife.

For fish ponds:

Install a filter and pump to keep your water clean and safe for fish. You can add a UV clarifier to reduce algae, or try an all-in-one pump that features a filter, pump, and UV built into one compact unit. Be sure to position your equipment so it's easy to access for cleaning and maintenance. Plant using a mix of marginal, submerged, and floating plants. Be sure to choose hardy, non-toxic varieties such as water lilies, irises, and hornwort. 

Tip: Avoid overplanting so that there is enough swimming space for fish and so that water can circulate around the entire pond.

For wildlife ponds:

Plant a mix of oxygenators, marginal plants, native plants, and floating plants. Decorate with natural materials like logs and stones to encourage biodiversity and keep your pond looking natural. Plant at different levels including shallow, mid-depth, and surface to create shelter for different species. Keep part of your pond shaded with plants or a cover to prevent overheating in summer.

Tip: Try to avoid plastic ornaments or ornamental gravel; wildlife ponds thrive with natural materials and plants.

Adding fish to your pond

Wait at least a week after filling your pond for the water to stabilise. Starting with a few hardy fish is ideal, and be sure to monitor the water quality regularly during the first few months. Use a water testing kit to test for ammonia, pH, and nitrite, making sure the conditions are suitable for your fish before adding them to the pond.

Float the bag your fish are in for 15-20 minutes to slowly equalise the temperature before releasing them. Introduce the fish slowly, and avoid adding too many at one time.

Only introduce species that are suitable for the size and filtration capacity. For example, Koi are large and messy fish, and tend to require specialist equipment and very large ponds. Koi, goldfish, and orfe are all popular choices for garden ponds.

Stuck choosing your fish? Try reading our help guide first.

Tip: Ensure you have shelter such as lily pads, floating plants, or planting baskets so fish feel more secure.

Maintaining your pond

Keep your pond at its healthiest by:

• Cleaning filter media in pond water regularly
• Topping up the water as needed in warmer weather
• Removing debris with a net
• Ensuring insulation or enough depth in winter to prevent it freezing solid

Tip: As the seasons change, so do maintenance requirements. Adjust your maintenance routine to suit the weather conditions, such as removing leaves in autumn and monitoring water levels and algae growth in summer.

Ready to get started?

Building a pond may seem daunting, but the steps are very simple. With the right planning and equipment, you can enjoy a peaceful, natural feature in your outdoor space for years to come.

Pond Building Checklist:

⬜Choose between wildlife or a fish pond
⬜Pick a location
⬜Plan size and depth
⬜Dig or build structure
⬜Add underlay and liner
⬜Fill with water and dechlorinate
⬜Add plants and equipment
⬜Wait 7-10 days and test the water
⬜Introduce fish if the levels are suitable
⬜Start regular maintenance

Shop pumps, filters, and UVCs for a healthy and clear water now, and browse our range of aquatic plants to complete your pond build.