Pond liners are used in koi ponds to hold water and prevent it from seeping into the surrounding soil. They create a watertight barrier that allows the pond to retain a consistent depth and volume. Most koi ponds use flexible liners made of materials like RPE which can be shaped to fit the contours of the pond during construction.
These liners are laid over a smooth base, often with an underlayment material beneath them to protect against punctures from rocks or roots. Proper installation is important to avoid folds or weak spots that can lead to leaks. Once the liner is in place, it is typically secured around the edges with stone, concrete, or soil.
