Building a Garden Pond

Building a Garden Pond

Designing your own pond

Choose a design and theme that suits your pocket, your garden and the setting where you want the pond. You’ll find inspiration all around you – magazines, books, TV, the internet, other people’s gardens and of course, water gardening retailers.

Pond Sizing

How to measure your pond correctly?
Firstly you will need to calculate the m³ of your pond using the following formula

Average Length (m) x Average Depth (m) x Average Width (m) = m³

Calculate how much water a rectangular shaped pond will hold:

Calculate how much water a triangular shaped pond will hold:

Calculate how much water a circular shaped pond will hold:

rect pond

tri pond

round pond

A metres x B metres x C metres = Volume m³
(A metres x B metres x C metres) /2 = Volume m³
A metres x A metres x 3.14 = Surface Area in m²
Surface Area in m² x B metres = Volume m³

Once you have calculated the m³ of you pond you will need to use the following formula to calculate its capacity

Volume m³ x 1000 = Litres Capacity

Additional factors to consider:

If the average depth of your pond is less than 0.7m (2’4”) and/or in full sunlight, you may need a bigger system.

Depth less than 0.7m OR in full sunlight
ADD 25% to Pond Capacity
Capacity Example: Pond Capacity 1000 litres x 1.25 = 1250
Effective Pond Capacity = 1250 litres

Depth less than 0.7m AND in full sunlight
ADD 50% to Pond Capacity
Capacity Example: Pond Capacity 1000 litres x 1.50 = 1500
Effective Pond Capacity = 1500 litres


Lining your pond

All ponds need to have a lining to prevent the water from draining away. Modern liners, whether flexible or rigid, have eliminated the need for traditional clay and concrete linings. Once you know the size and shape of pond you want the size of liner needed can be calculated as follows:

Length = Max pond length + (depth x 2) + 1m overlap
Width = Max pond width + (depth x 2) + 1m overlap

e.g. If the maximum length is 2.5m, the maximum width is 2m and the maximum depth is 0.5m the calculation is:

2.5 + (0.5 x 2) + 1 = 4.5m Length

2 + (0.5 x 2) + 1 = 4m Width

So, you will need a liner 4.5m by 4m minimum. Don’t forget to allow the 1m overlap around the edge for anchoring.





1. Mark out the pond shape. Dig the sides at a slight slope. Check top is level.



2. Remove sharp objects and protect liner with a layer of sand.



3. Anchor liner with smooth rocks. Start to fill with water. Adjust anchors as liner fills. Tuck creases to keep liner tidy.



4. Lay edging stones to complete the appearance.

Comments are closed.