Water Heater Supply Piping

Newer installation (3 years).

What would cause this type of corrosion other than a poor install?

Wrong adapter dissimilar metals. Steel???

… Cookie

A leak due to not tightening the fitting properly.

A leak due to not using Teflon tape/compound.

Not using a di-electric union.

A little fast but not wiping clean all the flux that may have dripped down from the above sweat fitting. This would speed up the corrosion process and eat away at the metal surfaces due to the acids in the flux.

I see that as a possibility. The Heater is 3 years old by manufacture date. The Installation date is suggested 2 years ago.

The amount of corrosion (without leakage present) seemed unusual for being 2 - 3 years.


I was not aware that excessive flux (not wiped) could potentially cause the corrosion present.

It can but not likely unless their was A Lot of flux.

That is a lot of corrosion, so it would need some help, like not using Teflon tape and having a good leak or high moisture. (a leak or high humidity)

Also, how well is the vent working??? That could be a source of moisture (steam) comming up from the burner area in a humid basement, etc.

Basement was dry. No indication of water intrusion and/or excessive moisture.

The vent has potential as this is a 150 year old plus home. Chimney was recommended for further review due to other factors (including potential obstructions).

Can leaking flue gas cause this type of corrosion?

I do not have a picture of the outlet pipe. The corrosion was only on the inlet.

That is why I asked about the vent… Cold water lines in a basement get a lot of condinsation, mixed with the hot gasses that may or may not be going up the vent pipe could be a contributing factor leading to the corrosion that we see on that supply pipe.
(notice how the corrosion looks like it is kind of wind blown, away from the vent.)

The corrosion could be from a mixture of all the items we listed in the above posts.

Thanks for the Help.