On 8/1/2020 4:07 PM, %% wrote:


"Ed Pawlowski" wrote in message
...
On 8/1/2020 9:17 AM, TimR wrote:
This isn't a problem I need to fix, just a curiosity I wonder about.

We have a sink that is used lightly.Â* It never has the stopper in, it
is never filled, there is never a reason for it to have water enter
the overflow.Â* The overflow hole is on the near side, the faucets on
the far side.

And yet, it has developed a tan stain obviously starting at the
overflow and extending down towards the drain.

I don't see any sign water has ever come out of the overflow, nor do
I see why that would happen, but there has to be some reason for this.

Probably fumes from the trap and drain system.

Unlikely to be fumes if the stain is where liquid would run.

Put some water down it and flush it out and it may help.


WTF do you think is happening in that drain? You wash down all sort of
caustic and organic materials and they sit in the trap where that
overflow connects. Some washes back in the bottom of it. sits and
oxidizes. Then it gives off gasses that rise and coat things.