Our pick for the best overall pond liner is the Firestone EPDM Rubber Pond Liner for its 45-mil thickness, weather resistance, and large 15-foot-long by 10-foot-wide size.

It holds 268 million gallons of treated water, and is used for irrigation. However, that pond has a liner that is damaged, and is now leaking water from the pond, to the North Fork of the Payette ...

If the water level in a lined pond drops or the flow of water decreases, check that no part of the liner has slipped below the water level. If a pond is leaking, it needs to be drained and inspected.