Pond liners can generally be used with both fresh and saltwater in a natural swimming pond, but there are a few things to consider. Most liners, like EPDM rubber and RPE, are designed for fresh water and can handle the conditions of a natural pond environment without issue.
However, saltwater is more corrosive and can break down some materials over time, so it's important to choose a liner specifically made to withstand the harsh effects of salt. There are special liners made for saltwater applications that are more resistant to damage, so using one of those will ensure the liner lasts longer and keeps the pond sealed. If you're considering a saltwater setup, make sure to check the liner’s compatibility with saltwater to avoid premature wear or degradation.
