I would use NSF-rated poly pipe. Depending on your water pressure, you could use 125 psi or 160 psi, and pull the pipe like for a sprinkler system. The heavier the pipe wall, the more difficult it is to clamp. The "Loxon" strap clamps made by Ideal are strong enough for this. There are also brass compression fittings for poly pipe, made for the waterworks market. They are as reliable as they are expensive.