While EPDM liners don't always neccessitate use of an underlayment, they can be used to help protect and cushion the liner. Underlayments can protect your liner from sharp objects, roots, or other damaging materials found in the underlying soil. Extra cushioning for the liner can also help extend its lifespan and prevent damage from excess stress. An underlyament can also help stabilize the soil underneath the liner to prevent shifting or sagging.
Using an underlayment may add to the overall cost of the project installation, but may save you money in the long run as it prevents the need for repairs or even replacement. While an underlayment may not be strictly necessary for every EPDM pond liner, it can provide additional protection and support that will help to extend the lifespan of the liner and prevent damage or leaks. Make sure to choose an underlayment that is compatible with the liner you choose, and follow the manufacturer's instructions for installation.
