If you look at the picture of the pond loop on the site you’ll see the design of the loops.
http://www.waterfurnace.com/residentialloops.asp It is very ridged polyethylene pipes and you'd have to try to damage it I think. My line was buried 5' underground to the pond. My pond was not filled at the time so they came out all most at the bottom of it which is 12 under water now. I have three loops which are basically 4' diameter loops side by side. So the area it takes up at the bottom of my pond is 4'x12' and that's all. It is a great setup and we’re very pleased with it.
Go talk to a dealer in your area and I’m sure they’ll show you a piece of the pipe and a unit.
