Corrosion of supply and drain. Cause?

Saw this in a newer (2004) condo building. In one unit only, rear bedroom master bathroom basin. It was a double basin vanity, but only one of the basins displayed this.

Supply (from valve to faucet) were steel tubing and the drain was steel. There was a green pateena on the supply pipes and the drain had green and black. The hinges for the door also appeared to be corrosed, but not with rust.

No Chinese drywall (not used around here) and only one of the two basins were affected.

Any ideas?

May have been keeping corrosive are caustic supplies under that sink.

Any other sinks/drains this way? Could be storage of epson salts and combination of high moisture.

I was thinking stored chemicals with the hinges like that and no visible damage to the cabinet or walls. Looks like a new tail piece, but can’t get over those hinges.

Comet or any other Chlorine based household cleaners in the cabinet

was the bottom of the cabinet wet or was that dirt?

Epson salt would absorb moisture. I agree that it is likely due to stored chemicals under the sink.

The floor of the vanity was not wet when I inspected it and no deformation.

I am leaning towards a chlorine material. That would explain the green corrosion on the steel. I was confused because green is usually copper oxidation.

Maybe some chlorine based drain cleaner or comet that got wet and the chlorine gas was released. Single guy in the unit and you know how they can be. :mrgreen:


likely a product containing chlorine bleach stored under the sink

Chlorine product is my guess - Chlorine from pools often corrode brass door hardware in the immediate vacinity, and rust metal doors and hinges. Something stored under cabinet with chlorine. could even be some 409 with bleech sprayed under cabinet to kill some fungus growth and not wiped off.

Most bathroom cleaners contain bleach (chlorine). :mrgreen: