Pond Underlay increases pond liner life and makes liners more puncture resistant by protecting them from sharp objects in the soil. Pond liner underlay also stabilizes ground under the liner to keep EPDM and other pond liners from over-stretching. It is quick and easy to install, and unlike newspaper or sand, pond underlay resists pond settling, decomposition and shifting. Keep your pond liner protected – purchase 20' wide pond liner underlayment today!