I have a black stain in my showerstall - a few years ago the basement in the house I'm writing about was renovated and an additional bath was installed - it consist of a toilet ,sink and shower stall - now the pipes that "feed" the bath are white pvc lines , the rest of the house is copper , why they used pvc I'm not sure - but probably related to cost - what is happening is the unit in the basement is used as a rental , and about every year they get a new tenant , so between tenants the unit could be vacant for a month or two - while the homeowner does go to the basement and flush the water - its when the water is turned off in the shower , the shower head does "drip"its during this drip when the black spot appears , its very hard to clean - I thought maybe the pvc pipes had something to do with it or maybe the showerhead - it only does this in the shower ( so the homeowner says ) and I personally have witnessed the stain - I even once replaced the shower valve to fix the drip , but it's a moen - and history ( with me ) has it that moen faucets drip - so I'm asking if any one has ever encountered this - the water system is county water , it has an electric hot water heater which was replaced around the time that this addition was installed

What you see might be minerals from the well water that you've let build up. I'm more interested in this,
history ( with me ) has it that moen faucets drip - N OT SO! We install Moen faucets on all our new construction wit no dripping complaints,
Try this for that drip. Shut the water off and remove the cartridge, Now turn the water back on for a few seconds to flush out the supplies and open valve, Reassemble and test.
I should have asked earlier. This drip, is it a steady drip or does it simply drip for a few moments and stop. Let me know. Tom

What you see might be minerals from the well water that you've let build up
- did you bother reading the post ? Once again "county water " supplied - that means "no well "

And every single moen faucet I have ever had to deal with drips - this is a consistent drip I timed it about every 30 seconds - it never stops

Well thanks a heap for giving me a reddie and jumping all over me . Do you have any idea how many questions we face in a day? That's OK! A smart dude like yourself ought to be able to figure this out by yourself without any help from us. As for me? I'm out of here!