How to Calculate the Pond Liner Size You Need

pond liner sizes

Pond liner is by far the best choice for most ponds where you want to create something unique and to suit your garden design.

Just make sure you work out the size you need without making a mistake.

Even though you can easily use pond liner to make any shape of pond it is always best to stick with designs that are not too elaborate. In general try to avoid sharp edges and too many indents.

See how to size the liner below.

IF YOU NEED HELP TO SIZE THE LINER PLEASE  call us on 0860-666-988 (email: We will work out the size you need while you're on the phone and give you a quote immediately. ...

The Best Pond Liner in South Africa

The best type of pond liner material available in South Africa is made from polyethylene and is the same material used to construct large dams and golf course lakes. We have extreme UV conditions in South Africa and choice of pond liner material is critical.

When you've decided where to site your pond (full sun is always preferred especially if you intend to keep water plants) the next step is to create your shape using a hose pipe or ribbon. Then record the maximum length and maximum width. Decide upon the depth you need ... 1.0 to 1.2 metres (3 to 4 feet) is a good depth unless you're building a large pond and intend to keep koi then 1.8 metres (6 feet) is a better option

To keep the cost of the pond liner down bear in mind that pond liner comes in rolls 7 metres wide. This means you can order any length normally in the following 3 widths: 3 metres wide, 4 metres wide and 7 metres wide. If a width more than 7 metres is required we can arrange this for you by having different widths welded together. It is not possible to use any kind of adhesive to try and join polyethylene liner together yourself.

Finished liner pondSee the 9 stages of completing a liner pond using real images ... click here. See image of finished pond to the left

Think About Depths and Planting Shelves

Sooner or later you will want to put some pond plants into the water. Some are best suited to water of about 0.9 metres (3 feet) depth such as water lilies while other prefer only 15 cms (6 inches) of water. So build in some shelves at different levels and also consider creating a bog area around the edges of the pond.

Use the method outlined below to decide what size liner you need to buy to fit your desired pond size (all pondliner comes in square or rectangular form).

See sketches below

The width of the liner

Gentle Reminder: A pond has depth and the depth applies to two sides wide and 2 sides long. This means if a pond is to be 1 metre deep then you will need to allow 2 x 1 metre for the width direction and also 2 x 1 metres for the length direction..

pond liner sizes

Take a look at the sketch again ... width is defined as the MAXIMUM width. So take your measurement at the widest point of the pond. The liner must overlap on both sides of the pond by at the very least 50 cms per side. The final material used for edging (stones, wood, brick surround etc) will be placed on top of this overhang. You must then also add the MAXIMUM depth and the MAXIMUM depth again. For example if you want a pond 4 metres wide and 1 metre maximum depth the width of liner will be 4+1+1+0.5+0.5 (for edging) = 7.0 metres.

Length of liner required

Just repeat the calculation as for the width. For example if you want the above pond to be 6 metres long then the length of the liner must be 6+1+1+0.5+0.5 (for edging) = 9.0 metres.

The final sheet size you will need to buy is then 7 metres by 9 metres.

It's probable that some of your pond liner will be wasted but don't throw it away. It will come in handy if you want to construct a waterfall


Landscape ponds with flexible pond liners to construct wildlife pools

flexible pond liner and V notch edging

 When you landscape ponds for natural look and wildlife access with flexible pond liners make sure you get the edging of the wildlife ponds correct.

Creating a "V" notch in the flexible pond liner designs allows for access into and out of the pond and a place to plant effectively.

Landscape ponds this way and you can create a garden pond that blends into the surrounding garden area as if the pond had always been there.

pond liner v notch

This photo shows "V" notch filled with sand and pond filling with water. Marginal plants are best planted in sand/soil mixture.

Notice uninterrupted, natural transition from water to edge of pond (lip of "V" notch) allowing access by wildlife

Pond liner installation Installing a liner to make a more formal pond is a bit trickier since you need to create a structure to form the basis of your final pond shape and position (ie above or below ground). If you click on this small image then a larger image, taken from Peter J May's "Perfect Pond Recipe Book", will open. This image provides good instructions to follow when building a more formal liner pond.

Aquamat an alternative to plastic liner

An alternative to plastic liner and something which looks more natural for a wildlife pond is Aquamat available from us. This is a bentonite and clay fabric that when wettened becomes completely impermeable to water. In the old days of pond construction long before the advent of flexible pond liner bentonite was used extensively to construct ponds using a process called "Puddling".

Aquamat is sourced from the largest Bentonite producer in the world. Aquamat is a geosynthetic clay liner with high performance environmental protection characteristics. It consists of a geotextile or geomembrane carrier which is compounded (needled is the correct technical term) with a layer of low permeability Bentonite and another layer of geotextile.

The natural Sodium Bentonite’s high swelling capacity and low permeability provide an effective hydraulic seal. The Aquamat has a thickness of less than 12mm, and it provides a better hydraulic performance than several feet of compacted clay.

Overlapping of Aquamat using the edges of the material allows larger pond linings to be achieved without the need for any special taping or adhesives to glue sections together. There is no need for underliner.

When Aquamat is used it is important to layer 12 inches (30 cm) of soil/sand on top of the Aquamat.


It is impossible to install a liner pond without pleats. Don't worry ... you won't notice after a short time.

You must install a felt like material underneath the floor of the liner to prevent sharp stones coming into direct contact with the liner. We suggest you use the best material available (as used in large installations). It is called Bidum and is also available.

If you want help to size your liner please call 0860-666-988 or fax dimensions of your pond ... width, length and depth in METRES Please also state if you want underliner.