How to install your new pond liner
Ponds are so good for gardens and people. They provide a focal point in water garden design, a recreational area, somewhere to keep fish, and grow aquatic plants.
Ponds also provide water movement and that all-important refuge for native wildlife.
The flexible pond liner is fundamental to every pond as it’s what keeps the water in, hopefully for decades to come. So its important that its installed correctly from the off.
How to line an in-ground pond liner
First prepare the hole by removing any sharp stones, tree roots and anything which could puncture the liner. Look around the edge of the pond.
Are there any fast-growing trees or bamboo that could send out as roots into the liner in the future? If there are then they should be removed or relocated now to avoid problems in the future.
Remember no pond liner is guaranteed against puncture, even if it comes with a lifetime guarantee.
Should I use sand under the pond liner?
Rake the soil edges and base of the pond to remove any remaining stones. Sand can be used to further even-out any undulations and provide an even smoother ground surface prior to lining. But its not essential.
Can I line a pond with old carpet?
If you have some old carpet to hand, now is the time to place it in the hole. Ensure there are no carpet tacks, gripper rods or nails left on it. But again the use of carpet is not essential and its not a viable alternative to proper liner underlay when it comes to longevity of the liner on top of it.
How to install pond liner underlay
Pond liner underlay is the best material to put down underneath flexible pond liner. Its purpose built, long term tested under millions of ponds all over the world and we at Swell UK recommend it to be used under every lined pond, large or small.
Unlike garden pond liners which come in one correctly sized sheet, underlay is often sold by the running metre, from a roll which is two metres wide. If your pond liner is only two metres wide its easy, but if its wider it will take a little bit of maths, and cutting, to lay the underlay down correctly.
If the liner is 4x3m for example, you’ll need 6x2 metres of underlay. Cut the underlay strip in half, so you’ll have two 3x2 metre strips, then place them in the hole. Cut underlay doesn’t have to be restitched together and as long as the edges meet that’s fine.
If you have enough spare, weight the edges down with stones then step into the pond and form the underlay around the edges. It doesn’t have to be exact.
Spare underlay can be used on any angles or stepped edges and sticky tape can be used to hold them in place until the pond liner goes down on top. Don’t trim off any excess yet.
How to install a flexible pond liner
Pond liner is best installed on a dry, sunny day. Being black, pond liner heats up in the sun and becomes even more flexible when warm. Carefully unpack the liner and lay it out on a snag-free, level area next to the pond. Always lift pond liner - never drag it - to avoid the risk of puncture.
With two or more people lift up the liner like a bed sheet, move sideways together over the hole and lay it down gently into the hole. Flexible pond liners should have overlap on every side so adjust it until there is at least 30cm of overlap over all the edges of the pond. Gently pull the liner in every direction to minimise creases.
Take shoes off and climb down into the pond, smoothing out the creases where possible. Start in one place and fold the creases neatly either clockwise or anti clockwise around the pond.
Climb out and then, using a hosepipe, start to fill the liner with a couple of cm of water. This will weight down the liner at its deepest point and again, using two or more people, pull the liner in every direction as it fills to further reduce any creases.
Weigh down the liner at ground level with heavy objects to keep the liner taught, then continue to fill up until the water level is about 5cm from the edge at ground level.
How to trim garden pond liners
Remove a 30cm perimeter of turves all around the pond edge but don't discard. You’ll need this for later. Using sharp scissors or a sharp craft knife carefully cut both the pond liner and the underlay underneath to make a neat 30cm overlap all around the pond.
Cover the trimmed liner overlap by replacing the turves on top or place paving, sleepers, landscaping rocks or capping stones right up to the water’s edge all around for a neat finish. The perfectly designed and lined pond won’t have any pond liner showing once filled.
How to fit pond liner in a raised pond
If you have a raised pond the same measures can be applied as for a ground level garden pond, detailed above. Use pond specific underlay to line the pond first, then carefully manoevre and lay the sheet of pond liner on top.
For timber framed ponds pull the liner tight around all the edges once filled, screw down wooden capping on top and then trim the overlap underneath the capping for a neat job.
How to fix a hole in pond liner
Accidents do happen and if the pond liner is punctured or slashed during placement, it can still be fixed. Locate the damaged area and use pond liner repair tape and a patch (cut from spare liner overlap, to patch it. And if you haven’t got any of that don’t worry as patches and sealant can also be purchased separately. Rubber pond liners, Butyl and PVC can all be repaired.