OK .. I'm going to be the odd man out here, but... When PEX became available, my employer had us use it instead of 3/8 copper to supply food service equipment. It was great to use, and cheap. All went well for a while, and then we got a few calls about leaks. Some were due to those "gator grip" type push in fittings eventually nicking thru the pipe wall where the tiny spring disk grips it. I'm sure the suppliers addressed that by now. However some of the leaks were strangely right along the pipe run somewhere. Leaks in a ceiling or, behind a wall were showing up. I had occasion to run about 100 feet to a food tiki hut on a golf course, 99% buried and the last 2 feet exposed as it went into the hut to the equipment. They had us remove the EQ because the pipe was leaking in that 2 foot section after a few weeks. It finally got to a point where we no longer used it. Now' I'm no rocket scientist, but some of my relatives are, and I had an occasion to ask about PEX he had used for his radiant heat. Usually when I ask this guy about something, I get lost about 3 sentences in. So here is the gist of the matter. PEX pipe is manufactured in such a way that an entire length of pipe is similar to one continuous molecule .....unbroken. This is why it doesn't "glue" well. If/when Pex is exposed to ultraviolet light, apparently the energy is just right to cause some of the atoms to lose their grip on their neighbor. After a while this "imperfection" "can" spread and eventually, depending on how long and how strong the UV exposure was, pinholes or worse will appear. This is why the stuff works so well buried in concrete floors for example. The real dicy part is U have no way of knowing if that pipe was stored on a shipping dock or somewhere else and received a dose of UV before it ever reached U. Even a regular exposure to 40watt florescent lights 6 feet away has caused a pex air line in my home shop to fail..pinhole..and only where the light falls on it!!! I have received similar warnings from other sources. As much as I liked the convenience of that stuff, I will never use it for anything again.