Pond liners can be made to fit practically any sized pond and there are a number of choices when it comes to choosing your pond liner, many of them come with a life time warranty and can be very cost effective.
The types of liners available on the market are:-
1) PVC - This is a budget option pond liner which can be purchase in 0.5mm and 0.8mm thickness. A PVC pond liner can be folded and taped to fit your pond and is suitable for smaller ponds, it is advised that you use pond underlay with your PVC liner to ensure that it lasts as long as possible. This type of pond liner does actually come with a lifetime warranty but this will be subject to correct usage and care. PVC pond liners are available in a number of sizes but these sizes are restricted to a maximum of 25m X 12m in the 0.5mm, and 25m X 10m in the 0.8mm, it is not recommended that you try to exceed these sizes by attaching 2 pieces together, if you do require a larger liner then it would be advisable to choose either a Greenseal or Firestone rubber pond liner.
2) Greenseal - This liner is probably the closest to Butyl, as Butyl pond liners are not often an option anymore due to the import costs other liners have been developed to take their place and the Greenseal pond liner is really the next best thing. The Greenseal pond liner can be purchased in thickness of 0.75mm or 1mm and is a textured rubber pond liner that is easy to fold and shape to fit your pond.
Also with a lifetime warranty (subject to care and usage) this liner is available in 8m width X up to 40m length and you can purchase 2 sizes and attach them together if you require a larger size. It is still recommended that you use pond liner underlay, this is simply to protect your liner from any objects which may protrude from the soil beneath.
3) Firestone - Available in 1mm thickness this liner has a smoother rubber texture and although it can still be folded, it may be more difficult to position than the 0.75mm Greenseal simply due to how thick it is. Although this is the toughest pond liner in the market place it is still recommended that a pond liner underlay is used. The Firestone pond liner also has a lifetime warranty subject to care and usage and is available in 15.24m width and up to 30.48m in length.
4) Box Liner - The advantage of these liners is that they fit to the exact size of your pond and are ideal for odd shaped ponds. The only disadvantage is that you may have to pay a little more and wait a little longer, but when your liner arrives at least you will be able to place it straight into you pond with little messing and no creasing. You do have to be spot on with the measurements that you give for your box liner, in fact you have to be to the exact cm or you will find that you have to dig a little further or fill in your pond so that your liner fits.
5) Pond Liner Underlay - This is a vital purchase with any of the pond liners as it will help to protect your pond liner from any foreign particles such as rocks and roots in the soil underneath. You should always try to remove as many objects as you possibly can from the soil to try to reduce any damage being caused to your liner, as even though the underlay will provide much more protection than not having any at all the underlay could still be damaged causing risk to your liner. Underlay is always the best option of protection for your liner as it will not rot over time and so should always provide a protective barrier for your liner as long as you need it.
There is also the ability to extend or fix your liner into the desired shape, to do this you would need 2 items which are quick prime plus and form flash repair tape. These items should be used in conjunction with one another, quick prime plus is an adhesive which needs to be pasted onto your pond liner, the attaching/folding piece of liner is then placed on top and you then seal this with the form flash repair tape. You can also purchase tools to assist you when doing this such as rollers which will help to secure the liners together as securely as possible.
If by any chance your liner does spring a leak, do not despair as there are ways which you can fix it. First of all you will need to establish where the leak is coming from; you may have a good idea if for example you have dropped something sharp into the pond. If you think that the damage is toward the top of the pond you could choose to let the pond drain of its own accord until it is below this level, then add baking powder along the part of the liner where the water has drained and the leak will be highlighted with a damp spot as water can still seep through from the underside of the liner. To repair the liner you will need a PVC patch if you have a PVC liner or a rubber repair kit if it is a rubber pond liner, these kits create a waterproof barrier and so your liner will again be able to hold water with no problems.
Keep in mind though that if you are unsure where exactly the leak is you really shouldn't just let the water drain as if it is lower in the pond liner then you could risk killing any fish you have in your pond. If you do not know where the leak is it is recommended that you filter the pond water into a holding tank and also transfer your fish. The pond liner then can still be repaired in the same way as mentioned earlier and if you do find that you have to drain the entire pond then it might also be a good idea to do any required pond maintenance whilst you are there.