I hope someone can help me or at least point me in the right direction. We built our house in 1999 (completed) and the house is plumbed with PEX. In the last six months, the PEX line coming from our water heater has split three times (hot water side). Each time we have had it replaced and each split has been farther down the run each time. The entire affected length appears to be approximately 4 feet. The water heater is in the attic, we are on county (treated) water and live in central NC. We have a PRV and expansion tank. The splits are not near a joint, fitting or bend and are lengthwise (almost like a seam "split" ) at about 1-2 inches in length. I am not sure who the manufacturer is ( there is a logo I am still trying to ID for contact info), but my plumber says it looks like CPI (NIBCO) pex. The manufacture date on the PEX says October 1998 (we started building in September 1998). We have not had any problems anywhere else in the house... Has anyone ever heard of such a thing? I thought this stuff was supposed to last a lot longer. I know that if PEX is exposed to sunlight it can be affected, but I am pretty sure this was not the case when our home was built... I have tried to include as much info as I can... Any help would be greatly appreciated... THANKS!!!