I recently took a look at our water heater (3-4 years old, gas), and the hot pipe coming out of the top is covered with the kind of corrosion I often associate with car batteries. Is something not properly grounded? How much of a problem do I have?
Are you referring to a white powdery substance?
It may just be the result of the last installer using a mildly corrosive flux when soldering a fitting and not wiping it off the pipe well enough before he left.
Go at it with some warm water and detergent and a kitchen "scrub sponge". If you clean the pipe off well it'll likely not return.
HTH,
Jeff
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