This summer I'm going to make a pond outside with some plastic sheeting from lowes
I've heard of people trying this, and other DIY pond liners, 9/10 doesn't end well. 1 guy had a blue heron tear through his plastic sheeting lol so he said. Randomly his water started going down a little bit every day. All he could think of was the heron always pecking around in the shallow area where the holes were.