Q: Can PEX piping be used for outdoor applications, such as a water garden?
A: The PEX material can be used outdoors if it is buried or otherwise protected. PEX piping can deteriorate in the presence of ultraviolet rays, so it should not be used outdoors if it will be exposed to sunlight. That old standby, copper piping, not only resists corrosion but is also unaffected by ultraviolet rays, which is one advantage copper has over PEX. Copper would be better suited for any outdoor lines that will be exposed to the sun. You should also install a back flow prevention device to make sure no water from the pond can be siphoned back into your drinking system.