Installing a pond liner

Getting Started

Dial before you dig - It’s important to know where the underground services are located prior to excavation so contact your local authorities.

Ensure you have all the tools needed to dig your hole, and have made allowances for the amount of soil you will be removing.

Installing a pond liner

Clearpond - Installing a pond liner

Use a hose, sand or line marking paint to mark out the area you intend to build your pond. Determine how many steps or shelves you would like within the pond before digging to the desired depth.

These steps can be used as plant zones and for exit points should any wildlife fall into the pond. If using steps, the first one should be around 20-45cm in depth, creating a shallow water zone for marginal plants. Further steps can then be dug out or the pond taken down to its final depth.

There’s no set rule for how deep a pond should be, but in general, the deeper the pond the easier it is to maintain. Koi ponds do have special requirements and should be 1-1.5m deep. Remember to check with your local council to determine if they have any regulations governing the depth of ponds.

Now that you’ve dug your hole, its time to shape it. Take this opportunity to ensure there are no sharp objects, roots or rocks on the base or side walls. Use a spade to clean up and get the hole as smooth as possible. The more time you take to get this right, the easier it will be to get the rest of the job done.

Consideration should now be given to any plumbing and electrical cable trenches that are required for the pond equipment. Pump cords and plumbing can rise up and over the pond edge and be hidden by capping but in most cases the hose and cable are visible. Another alternative is to use the Tradux from Oase which enables pipes or electrical cables to penetrate the pond liner through a water tight seal below water level.

Whatever method used, you should follow all regulations regarding electrical power cables or if unsure, contact a certified electrician. The length of the cable of any products used for the pond such as pond pumps and pond lighting should not be altered. Please contact your supplier before cutting any plugs or cords.

Clearpond - Installing a pond liner

When considering plumbing you should think about the type of pond filter being used i.e. pressurised or gravity fed. Further information regarding filtration systems can be found in our FAQ section or by discussing it with your local retailer. Please seek advice regarding pond filters before you finish off the surrounding areas of your pond to make sure any plumbing has been allowed for.

Clearpond - Installing a pond liner
Clearpond - Installing a pond liner

Before you put away the shovel you should create a capillary barrier to prevent run off entering the pond and polluting it with fertilisers, pesticides or other products used in the garden. Start by digging a 15cm wide x 15cm deep trench around the outside of the pond approximately 25cm from the pond’s edge. After the liner has been installed you will fill this trench with blue metal or other decorative pebbles which will allow the garden run off water to bypass your pond and continue on its natural path.

Now that you’ve dug out the pond, capillary barrier & trenches for cables and plumbing it’s time to work out how much liner you need. The easy way to do this is run a string line from one end of the pond to another making sure the string keeps contact with the ground and the contours of the pond.

Then remove the string, pull it tight and measure it. This will tell you the length of required liner but remember to add an extra 30-50cm for overhang and fixing into the capillary barrier. You’ll need to do this for both the length and width of the pond.

When purchasing your liner (PVC or Proliner EPDM)  it’s recommended that you purchase the same amount of pond liner underlay. Pond Underlay will provide a protective barrier between the ground and liner and reduce the chance of tree roots or rocks penetrating the liner.

Now that you’ve measured and purchased your underlay and liner, the next step is to install the underlay. A handy tip is to wet the under lay to prevent it from blowing around while you’re installing it. Roll out the lengths of underlay so that you have complete coverage of the pond base and side walls. If you have any large folds or double overs, take the time to trim these out now as this will allow for a neat lining without any unnecessary lumps underneath. You may choose to use tent pegs to hold the top of steep side walls in place.

Sand can also be used to protect pond liner but it can’t stick to walls and therefore provides no protection to the side of the pond. It’s also labour intensive. Pond liner underlay is much easier.

Clearpond - Installing a pond linerClearpond - Installing a pond liner
Clearpond - Installing a pond linerClearpond - Installing a pond liner

Once the underlay has been installed it’s time to lay the liner. The liner is laid directly on top of the underlay and pulled so it is taut. when laying the liner across the pond, make sure that the liner rests on the bottom, walls and shelf edges. Place smooth rocks around the edges to keep the liner in place, fill slowly with water and move the rocks back as the pond fills.

Pleats will start to form in corners and curves smooth these out as you go around the pond. Adjustments to the liner should be made while the pond is filling. This ensures there’s enough weight to pull and adjust the liner without too much weight that prevents the liner being moved. It’s too late to adjust the liner when the pond is filled! If done correctly , they will hardly be visible once the pond is completed. Stop filling when the water level is about 10cm below the final level.

Now that the liner has been secured with the weight of the water, you can finish off the edges as planned, you can trim off any excess liner and underlay. Trim the liner so that the edges can be placed within the capillary barrier and weighed down by the blue metal or pebbles that will then fill it. Bog plants can be planted in the capillary barrier. If you plan to place any large rocks within the pond you can use the off cuts of liner to provide extra strength underneath.

For joining liner, we have videos on our YouTube channel - click here

Clearpond - install liner
Clearpond - Installing a pond linerClearpond - Installing a pond liner

Edging or capping can now be completed. You can use many products to edge a pond such as wood, paving or natural stones. Whatever you choose remember that people will be standing on these surfaces looking into the pond so make sure they’re strong underfoot.

With the pond filled and edging completed it’s time to plant out your pond. It’s a good idea to have a mix of marginal plants that rise above the water, surface spreaders whose leaves spread out over the water and full aquatics that are totally submerged.

A third to two thirds of the pond should be covered by plants but be careful if you’re considering Koi as they’re known to make a meal of plants. If you do have a Koi pond you can still have plants in your system by using our floating rings that float on the surface and protect the plant.

Pump and filtration systems should now be connected and turned on with the exception of UV lights. UV lights are left off for a period of 4-6 weeks so that the beneficial bacteria have a chance to build up in the biological filter. Further information on pump filters and UV lights can be found in our FAQ section.

It’s a good idea to let your pond establish itself for a week or so prior to introducing fish but if you can’t wait that long you can condition the water using treatments like our Clearpond Biostarter. Even after using these products you should only introduce a few fish into your pond so you don’t shock the system and potentially harm your fish. Additional fish should then be added every couple of weeks until you reach your desired amount. A general guideline is no more than 1 kilogram of Koi for every 1000 litres of water or 2 kilograms of goldfish per 1000 litres of water. The more fish you have the bigger the filtration system you’ll need.

Hopefully this guide has helped you build the pond of your dreams! Now you can explore the rest of the website and learn about the products and techniques that will help you maintain your pond and keep it looking as good as it did when you first built it.

Clearpond - Installing a pond liner Clearpond - Installing a pond liner

Hopefully this guide has helped you build the pond of your dreams. Now you can explore the rest of the website and learn about the products and techniques that will help you maintain your pond and keep it looking as good as it did when you first built it.