As many of you predicted, the PEX systems are experiencing failures at the fittings. Odd thing is it's the brass fittings that are failing. One company involved is Zurn, the brand sold at local big box hardware stores. Haven't read all the data, but at a glance it seems that the fittings are made in China (surprised?) and have too much zinc in relation to copper content (cheaper). In hard water areas the brass fittings are developing leaks caused by reactions to the mineral content. Another issue is that the threaded fittings were machined at too high of a speed, resulting in cracks and failures at the threads. Just type in Zurn class action suit in your favorite search engine. Here's a thread from a plumbing forum, hope it's ok to post it here for related reading. Zurn class action law suit. My sorry tale. - Terry Love's Plumbing & Remodel DIY advice forum