# Needs to be food grade since the water it stores is for drinking. <br>
#Cost: Polyethylene and Polythylene liners typically cost half that of Polypropylene and EPDM. PVC and PVC-E liners are the next step up from Polyethylene and polyethylene in terms of cost. Compared to other liners, PVC is somewhat more affordable, while being somewhat puncture resistant at the same time but in terms of durability, the typical 20-mil (i.e. 0.020") thick PVC is somewhat mediocre in terms of durability. EPDM is more expensive than Polyethylene, polyethylene, and PVC liners, but can last for up to 20 years. Polypropylene is an expensive material but can last for up to 40 years.<br>
====Material durability====
* Polyethylene and Polythylene liners typically only last one season.
* Polyethylene will readily conform to any shape, however, it does not have the sturdiness that is required for a permanent pond liner.
* Polythylene, on the other hand, is extremely rigid and can be stiff to work with. Polythylene can be damaged easily by rocks, and has to be handled
with care. If polyethylene is damaged, it cannot be seamed together without expensive welding equipment.
* PVC and PVC-E liners are the next step up from polyethylene and polyethylene, and they can last for up to 10 years.
* Polypropylene is an expensive material but it is the most durable pond liner material in existence because it can last for up to 40 years.
Polypropylene, however, is not as flexible as EPDM liners.
* EPDM (Ethylene Propylene Diene Monomer) rubber liners are recommended for most pond installations because of their delicate balance between
longevity, flexibility, affordability, and their lack of toxic plasticizers. Because EPDM liners are rubber-based, they are extremely flexible (much more so than PVC liners) - the extra flexibility of EPDM comes in handy when working with irregular folds and shelves that are commonly found in a pond. They also do not contain any plasticizers that can make the liner brittle and crack with age. A 45-mil EPDM liner can last for up to 20 years because of its natural resistance to UV, and its puncture resistance.
