In homes plumbed throughout with galvanized, there are many transitions to brass fittings or even combinations of brass and galvanized within valves and faucets. Accordingly, there are many junctions of dissimilar metals that can give rise to accelerated corrosion.

 

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Further images of corrosion scales on galvanized iron: utility 5

05_PFg10 cold side- click for full size:

 

05_PFg56 - galvanized fitting with bacterial remnants

 

 

05_PFg56 - SEM image showing bacterial filaments