I ran across this pipe with which I am not familiar. The pipe material appeared semi-translucent. There were no markings present. It did not seem to be PEX or CPVC. It could be seen only at the water heater at the cold and hot lines, as well as the circulating line. There was a brass elbow fitting visible near the circulating pump. The elbow was quite abrupt--a very small radius turn. It had rings around the connections to the pipe, but they didn't seem to be crimp connections. Does anyone know what this is and if it is approved for water piping use?
