Firestone EPDM liner is the standard for pond and water garden construction. UV treated, fish and plant safe, and equipped with a 20 year warranty. 60 mil is the thickest EPDM that we carry and is unparalleled in terms of puncture resistance. For the heaviest of duty koi ponds we recommend combining this with a geotextile underlayment for a nearly indestructible pond construction.
To Determine the Liner Size You Need:
(Max Length of Pond + (2 x Max Depth of Pond)) + 1 = Length of Liner Needed
(Max Width of Pond + (2 x Max Depth of Pond)) + 1 = Width of Liner Needed
It is always a good idea to have an additional foot of material on both the length and width of the liner to allow for error and to provide an overhang which allows the liner to be secured properly.