Thread: Corroding Copper Pipes

Any thoughts on reporting / recommendations for this one? Full basement of townhouse. No unusual corrosive chemicals or cleaners observed. No unusual corrosion on HVAC equipment or vents. Notice that trap arm emerging from under utility sink is not corroded. One possible clue in, in last photo, is that it appears that something dripping/running down the 2" stack has corroded in it's path. Also, the most corrosion is at or below the sink rim level, note that corrosion on the 3" stack rapidly tapers off above this level - I can't figure that one out.

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Flux not wiped off after soldering.

OK - but how did it run uphill onto the spout at the utility tub faucet? Get onto the packing nut at the valve?

That's not flux, but ...

The first thing to do when you see that is to take your clamp on ammeter and see what current there is, if any, through those pipes AND back at where it is bonded to ground (check them wherever you see them exposed).

It *could be* a ground problem.

It also *could be* an environmental problem with laundry detergent chemicals in the air and causing that on the copper piping.

*Usually*, with that green corrosion, it is chemical in the environment it's in.

"OK - but how did it run uphill onto the spout at the utility tub faucet? Get onto the packing nut at the valve?"

The Stem seal has a very small leak, so small that the water evaporates before a droplet forms, leaving behind the mineral deposits and forming the corrosion you see.

I agree with Jerry. The green corrosion is likely caused by fumes from bleach reacting with the copper pipes.

"Notice that trap arm emerging from under utility sink is not corroded."

The trap arm looks newer than the rest of the plumbing, I suspect the sink may have been replaced and with it the trap arm ( look at the legs on the sink, they look to good to be as old as the plumbing fixtures.

"Also, the most corrosion is at or below the sink rim level, note that corrosion on the 3" stack rapidly tapers off above this level - I can't figure that one out."

Again fumes from the bleach are heavier than air.

Originally Posted by Rick Cantrell

Again fumes from the bleach are heavier than air.

Did you also notice that the copper stack is only stained with corrosion up to just above the tub level?

Originally Posted by Jerry Peck

Did you also notice that the copper stack is only stained with corrosion up to just above the tub level?

That's about the most telling sign there.. there may be other problems too... but my vote is for something in the air in the room.

That's a humidifier of some sort on the furance ducting, right? I don't have many of those in my area (wet Oregon air) but do they ever leak or malfunction and spew moisture into the surrounding area?

Also, that seems to be a small room and we have to assume there are louvers in the door for combustion air... if not, could this be related? Or is there combustion air provided somewhere that is not clear from the picture?

And the biggest problem of all.... I notice the washing machine is set on a normal cycle and that appears to be a bottle of gentle cycle Woolite. They well may damage their delicates....

In all seriousness... It looks like something in the air rather than something in the pipes. Especially since it's on hot and cold supply as well as waste/vent piping.