i have a circa 1950's home that has failing galvanized piping and have been considering replacing it all with a pex system. however, i've found some disturbing information concerning the pex system that i was considering on using, and was wondering if anyone has any comment about this.
there apparently is a situation in nevada in which a large number of new homes were installed with pex systems. after just a couple years, it was found that dezincification corrosion was occurring on the brass pex fittings that are attached to the copper manifolds, causing leaking of the fittings to occur. corrosion appears as whitish and bluish deposits on the brass pex fittings. dezincification is effectively the dissolving of the zinc that is in the brass fittings, causing the fittings to fail. the mineral content in the water causes this to occur quickly or slowly. the fact that it occurs so quickly in nevada suggests that this will likely occur more slowly elsewhere.
other webpages on this site show photos of the actual corrosion.