The water in most of North America has a natural pH of 7 or higher, and has dissolved mineral in it such as Calcium and Manganese. Over time, these minerals attach to the inside of the copper pipe, forming a protective layer that keeps flowing water away from the copper. If the water can’t touch the pipe, the water can’t hurt the pipe!
Metro Vancouver has some of the best, safest drinking water in the world. It is beautiful to bathe and clean with, and Metro Vancouver does a great job filtering, sterilizing and delivering it to your tap. But this beautiful water has one inherent problem; it is extremely aggressive and hard on metal plumbing infrastructure. It is naturally soft (which means it has very few minerals in it).
Without these minerals, no protective barriers form inside the pipe and soon the soft water starts to attack the copper pipe, creating pinhole leaks. Furthermore, our higher temperatures and the higher pressures found in our water systems increases the speed of soft water corrosion.