Black particles in water: Navien tankless water heater to blame?

cry1130

Small black particles started appearing in our water a few weeks ago. Appears to only be the hot water. We have a Navien tankless water heater. I'm not sure the model but have attached a picture of the inside. Looks relatively new (we bought the house a year and a half ago). We had the Navien flushed/serviced. Did not fix the issue. We had the valve on the main water line into the house replaced as recommended by a plumber (in case rubber is the issue). House has copper and PVC pipes. No visual evidence of flexible/rubber lined piping in the home. We're not sure exactly what the particles are. I have attached a picture. They smear when you rub with your finger. Any ideas as to what this is and how to fix it?

Intplm.

Those particle are very hard to see. Are you sure the particles are only coming from the hot water ?

It could be that the hot water is extracting those black particles out of the water when the water is heated. The thing that I can't tell is how they smear when rubbed.

A few questions.
Have you had your water tested?
Is there a water filter and water conditioner on your water main?
Is this city water or a well?
From what water faucet did you take the sample from?
It could be normal build up coming through your faucets that is built up in the faucet aerators ?

Maybe remove and clean the aerators on your faucets ?

Try draping a white cloth like a handkerchief over a glass and turn the faucet on drawing water through the cloth? Then look at the cloth.
Hope these things help. Please respond back.

Alan (California Radiant) Forbes

Our local water department changed the disinfectant they add to the water from chlorine to chloramine (a chlorine/ammonia compound). The ammonia breaks down rubber, affecting various parts of a plumbing system (toilet flappers, faucet/water heater connectors, etc.); symptoms are like yours. Chloramine resistant fittings are now available.

What part of the country do you live in? Check with your water department.

Larry Weingarten

Hello, If you have any braided stainless flex connectors, they often have a black rubber lining that disintegrates just as you have described. An expansion tank could be another source of rubber too.

Yours, Larry