Three Generations of Pipe, One Water System

A typical house in this town runs original steel or iron from its first construction, copper from a mid-century or later renovation, and sometimes PEX from the most recent remodel, all joined into one pressurized system. The trouble concentrates exactly where they join.

When copper connects to older steel, the two metals form a slow electrochemical reaction with the water between them, and the Copper Development Association puts the mechanism plainly: galvanic corrosion can occur when dissimilar metals like copper tube and steel pipe are connected with water present, and it is rarely the copper that fails, which means the older metal at every one of those junctions is quietly sacrificing itself. Multiply that by every renovation the house has seen, and the leak map writes itself: the era boundaries fail first, the oldest generation fails next, and the newest keeps working through all of it.