A leak in your pond liner can be a big problem for you and your aquatic life as it could potentially drain all or most of the water.
Switch Off All Pond Equipment
A leak can be hard to find, so you must first top up the water in the pond and then turn off all pond equipment including pumps and water features.
Leave it overnight and check the next morning. If the level of the water has dropped then you know for sure it's a liner leak rather than leaking pipework, watercourse or filtration unit.
Finding The Leak in Your Liner
If the leak is obvious then the pond will probably empty very quickly. However, this isn't normally the case with a leaking liner, you'll usually find it's a pin hole and you're going to have trouble locating it.
The best way is to allow the pond to drain and, when the water stops leaking, examine the liner at the new water level. This will take some time as most liners are black and it's going to be hard to find an insignificant hole.
Repairing the Hold in the Pond Liner
If you find the hole then well done, now it's time to fix it. This part is relatively easy, the first thing to do is get a piece of chalk to mark the hole so you don't lose sight of it.
There are a number of ways to repair pond liner and these include a pond liner repair patch, repair tape or sealant with a patch of pond liner, all three are tried and tested so which one you use is down to personal preference.
Repairing the Liner with a Repair Patch
A pond liner repair patch is basically a large patch which has one sticky side. The smooth back gives the impression that it's part of the original liner. If you have multiple holes then you can simply cut this patch up using a standard pair of scissors, and you can also buy repair kits.
Pond Liner Joining/Repair Tape
Liner joining tape and adhesive are designed to join two pieces of liner together. The tape is also great for placing over a hole in your pond liner in a similar way to the pond liner repair patch but you're able to purchase it in smaller amounts making it more economic. The downside to this tape is that it's sticky on both sides as it's designed for joining two liners together, this means stones and debris can stick to it.
Pond Repair Sealant and a Patch
A more DIY version of fixing your pond liner is to use a patch of pond liner and some pond sealant. Pond Pride and Gold Label's pond liner sealant is perfect for this job. It even works underwater, ideal for repairing a pond without draining it.
All you'll need to do is purchase the sealant and a patch of pond liner. Put a bead of sealant all around the edge of the patch and then place it over the hole.