What is that stuff on my water heater?

Water heaters are one of the most important things for daily comfort in our homes. Who doesn't look forward to that hot shower in the morning to get you going for the day? We rely on our water heaters to work day in and day out throughout years of service and rarely think about them. They are usually hidden away in the garage working hard to make hot water for daily use and slowly corroding away.

Since they are so back of mind, it's a good idea to check on them every once in a while. Catching problems early saves you in the long run, emergency service calls by a plumber tend to be a bit spendy.

Something that is easy to catch if you look for it is early signs of galvanic corrosion at the supply lines. Galvanic corrosion happens when two dissimilar metals make contact in a wet environment. The supply pipes to a water heater are a prime location for this to occur.

Galvanic corrosion at water heater supply lines.

Close up of the corrosion.

Supply line connections repaired. New dielectric unions and teflon tape.

What causes it? Like the root of a lot of problems in a house - water. Obviously water flows through the pipes and it can act as a bridge for an electrical charge. The pipe connections have to be shielded from water. This is usually done with a dielectric union and teflon tape. In the picture above likely both of these safeguards have failed. 

This can be an easy fix if caught early. The dielectric union needs to be replaced and the connections need to be well protected with teflon tape. 
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I recommend watching this video from This Old House to learn more about this issue.

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