Home inspectors that have been properly trained will point out the fact of this issue to their clients.
It’s called Galvanic Corrosion where two dissimilar metals and alloys have different electrode potentials, and when the two or more come into contact in an electrolyte; (minerals in water) one metal acts as an anode and the other as a cathode. The electro potential difference between the dissimilar metals is the driving force for an accelerated attack on the anode member of the galvanic couple.
The electrolyte; (minerals in water) provides a means for ion migration whereby metallic ions move from the anode to the cathode within the electrolyte (like a battery). This leads to the metal at the anode corroding more quickly than it otherwise would and corrosion at the cathode being inhibited.
These reactions can be found if an improper installation of any pipe fitting has taken place.
The solution; would be for a good qualified Plumber to join the dissimilar metals with a dielectric union which would prevent the galvanic reaction by an insulating insert between the two metals to prevent electrolysis from occurring.
Mike Ritter
Owner/Inspector
Home Pulse Pro Home Inspections