Black specks in hot water?


We noticed black specks that smudged our tub and silicone dishes and noticed it was only when we ran hot water. It’s coming out from all faucets.

Upon research online we figured it had to be something with the hot water tank so we had a plumber come out to look. I initially thought it was the flex lines but we have copper flex lines so that’s not it. The plumber opened the flex lines to see some rubber rings that had deteriorated a little bit so he replaced that and flushed the tank a few times.

Fast forward a day later, there’s now way more black specks coming out - like if I put the pieces together it would be way more than that rubber ring so I don’t think that was the problem. I’m not even sure it’s rubber or not. When I put a piece on my finger and rub it leaves like a black chalk mark almost. Anyone have any idea?!

q black specks in hot water
  7 answers
  • Flipturn Flipturn on May 28, 2020

    How old is the tank?

    Did the plumber actually clean out the bottom of the hot water tank?

    Also, do you have a water softener?

  • Heather A Heather A on May 28, 2020

    I have the same issues and i have a brand new water tank. Its a brand new house. I dont know what to do but they smudge like a greasy waxy type of way.

    • See 3 previous
    • Flipturn Flipturn on May 31, 2020

      Hi Heather,

      When I re-read your comment, the fact that the residue is greasy or wax-like got me thinking that the source of the problem may be a build up of potassium permanganate.

      Please read through my answer below.

  • William William on May 28, 2020

    Oily, smudgy debris in your water is generally a clue that a flexible rubber hose somewhere in your home plumbing system is disintegrating. Chlorine or chloramine added to the water supply as a disinfectant will tend to eventually corrode rubber. The most frequent culprit in this situation seems to be the flex hose leading to your water heater. It is likely that you will need to have a plumbing professional replace the hose. Fortunately, the newer versions are usually protected with a water disinfection-resistant lining.

    Here is a discussion and possible causes and solutions

  • Kathy Gunter Law Kathy Gunter Law on May 29, 2020

    Did he drain your water heater? You are supposed to do that annually. Sediments build up in the bottom.

    • See 1 previous
    • Kathy Gunter Law Kathy Gunter Law on Jun 09, 2020

      I firmly believe newer ones are no longer made to last. Also, water composition can be a factor b

  • William William on May 29, 2020

    It could be the dielectric sleeve on the ends of the flex hose. Could be a gasket on the t&p valve. The discussion link has what other people found to be the problem.

    • Fina Kwan Fina Kwan on Jun 08, 2020

      The plumber replaced the rubber washers in the dielectric union but there’s so much black specks in the tank that it can’t be the rubber washer. I’m thinking we might try to drain it ourselves again before calling the plumber again. He mentioned the only other course of action is to run water through the house bypassing the HWT to see if black specks still show up (which I’m sure it won’t because the HWT was full of the black specks so I’m sure that’s the source). He said we may need to replace our HWT.

  • Simple Nature Decor Simple Nature Decor on May 30, 2020

    Sounds like rust from the pipes

  • Flipturn Flipturn on May 31, 2020

    The culprit might perhaps be a build up of potassium permanganate.

    It is a purplish black crystalline solid that is widely used in water treatment.

    Over time, and variances in water pressure, sometimes there is a build up inside the end pieces on individual faucets.

    Here's what I would suggest:

    -Remove the end piece, or mesh filter/aerator from the end of the faucet.

    -Remove the inner O ring and clean the area well

    -Clean the filter well (a toothbrush usually works well)

    -Run water through the entire faucet on 'full open'. Without the end filter, you should find that the water pressure is stronger than normal

    -Look carefully to detect any black residue coming out with the water

    -Continue running the water until it runs clear

    -Replace the ring, filter/aerator if they show signs of deterioration

    • Fina Kwan Fina Kwan on Jun 08, 2020

      We tried to smudge it more and it’d only pure black - no hint of purple at all. We noticed the most running our bathtub and we don’t have a mesh filter on it (that’s probably why we see it more here). It’s not limited to just one area as it’s in the hot water tank when the plumber came to flush it. He ran some water from the tank itself and a lot of these came out in varying sizes.