Temporary Pond Liners
Temporary ponds use thin liners such as 10 mil PVC to keep costs down. Thin polyethylene liners can also be used, but they are more vulnerable to pin hole leaks. Polyethylene liners will float, which allows more water to spread out under the liner and accelerates the loss rate.
The expected life of an exposed, thin liner is only a few months. If your temporary pond needs to last longer, use a 20 mil or 30 mil PVC.