Cross-linked polyethylene (PEX) tubing in 5/8-inch or ¾-inch diameter can also be used. Nylon fittings and stainless clamps will minimize the potential for leaks. Fittings that are buried below ground ...
PEX tubing is another name for plastic and according to Krieger, it helps with expansion and is not difficult to use. “You don't need as many fittings. You have very few couplers everywhere ...