White rust, which is a combination of zinc carbonate and zinc hydroxide, shows up as white spots and bumps on a galvanized surface. It is porous and generally does not protect a steel structure. Left unchecked, leaks can form in a cooling tower basin in as little as two months in severe cases.
The incidence of white rust damage to cooling towers has increased dramatically since the late 1980s. As such, U.S. Water emphasizes the importance of consulting a water treatment representative early in the process of purchasing a new cooling tower as multiple factors need to be considered before choosing the tower’s construction materials.