Cons: Rubber liners are fairly difficult to install; not all homeowners will understand how to glue and seam the liners together. A small mistake can result in a big drainage problem, and you’ll lose your water and fish. Burrowing rodents also can nibble through the liner. “You’d be surprised how quickly a koi pond will drain into the ground,” Leidner says.
Expert tip: If you do go with a rubber liner, Leidner recommends buying a few bags of concrete, poking holes in them and using the bags to line the hole. Then spray the bags with water and put the rubber liner on top. The bag will dissolve and the concrete will harden, creating a barrier that rodents can’t get through