The biggest contributors to pond liners failing are poor, unstable soil conditions and rips and tears from rocks and boulders. Shifting soil creates pockets and voids under your pond liner, forcing it to stretch under the weight of the water. Rocks and boulders when placed on and around your water feature create aesthetically pleasing visual focal points. They can also penetrate, tear and harm your liner. Protect your liner with Underguard Underlayment™!