Black Specs found in Tub and sink.

[jzwetow]

My mother-in-law has a rental property, and the tenant has been experiencing an issue where black specks appear when they run hot water in the back bathroom. This started several months ago. Initially, we suspected the water heater, so we replaced it. However, the issue persisted. When we replaced the water heater, we didn't replace the expansion tank. The new expansion tank we bought was too large, so we decided to leave the old one in place. After the tenant reported the issue again a couple of months later, we decided to replace the expansion tank.

For context, the original water heater and expansion tank were about six years old. A previous tenant had reported a leak behind the shower in the front bathroom, which led us to completely renovate that bathroom. We replaced the CPVC pipes with copper, and installed a new shower, vanity, toilet, water heater, and expansion tank. However, we did not remodel the back bathroom.

The current tenant hasn’t reported any issues in the front bathroom or kitchen, likely because the aerators are capturing any debris. The front bathroom is primarily used by their daughter and has a shower only.

The hot water heater is located between the front and back bathrooms, and there are no other appliances on the system, such as a water softener or whole-house filter.

Additionally, before we replaced the water heater, the tenant complained of water on the floor around the water heater and said the pressure relief valve had discharged water. We discovered that the tenant had turned the water heater temperature to its maximum setting, which we believed caused excessive pressure and the leak. After replacing the tank, they reported finding water on the floor again. We suspected they turned the heat up again, but when we checked, the temperature was set to a mid-level. We think they may have lowered it before we arrived. There has been no other complaints of water leaking from the tank for a couple months.

What could be causing the black speck. We are going over today to drain the system again and replace the supply lines to the water heater. Current supply line are braded nylon and will be replacing with braided steel.

 

[Twowaxhack]

Some water heater flex hook up lines will cause that.

 

[Geofd]

If the temp gets too hot it can deteriorate the rubber in the washers in the stems in the faucet, and the washers in the stop and waste under the sink that control the hot and cold

 

[Ludington]

I had this trouble (not quite to this extent) but when I unhooked my hot water heater lines, I found the rubber inside had deteriorated and was pretty much gone.. it gad made its way through my pipes and to my tub. So it's probably as the others have said, rubber deteriorating somewhere.
It will probably eventually clear , but you may end up with a leak.

 

[CentMontCo]

I had this trouble (not quite to this extent) but when I unhooked my hot water heater lines, I found the rubber inside had deteriorated and was pretty much gone.. it gad made its way through my pipes and to my tub. So it's probably as the others have said, rubber deteriorating somewhere.
It will probably eventually clear , but you may end up with a leak.

I had a problem with my Delta bathtub faucet, including black specks in the tub. I removed the cartridge & the check valve, and there was what appeared to be a deteriorated o-ring stuck to the back of the hot water valve in the check valve. Do you think it's at all likely this o-ring came from the water heater? When I cleaned it & put everything back together it worked fine.