VC pond liners are durable pond liners for your backyard pond. Over time, with wear and usage, a PVC pond liner may develop a rip or tear and need to be repaired. If the rip or tear is not repaired, the water will leak out of the pond and depending on how bad the leak is, the pond could empty fairly quickly. Also the leaking water could damage any nearby objects that aren't meant to get wet. Luckily, it is fairly easy to repair a PVC pond liner, and it is not very costly or time consuming.
http://www.pondpro2000.com/epdm-pond-liner.html