My tea kettle has a bunch of black dots all over the inside bottom part of it. I tried washing it and using a scrub sponge to scrub it off but it won't come off. Is it safe to continue using it or am I drinking stuff that's leaching from the kettle?

To better describe this, the black dots are small dots, like if you used a pen to "dot" a piece of paper. The dots are only on the inside of the kettle, the part that touches the water. It doesn't show up on the outside bottom of the kettle. The dots are all over the bottom, there's no one part where it clusters up.

I highly doubt it's mold. It could be rust but I'd think (but have been wrong many times) it would have scrubbed off with the scrub sponge. Thanks in advance for your help.

EDIT: Newly attached picture below enter image description here

  • 2
    What's the tea kettle made of? Stainless? Any chance of a picture of the dots? – derobert Apr 17 '14 at 17:09
  • @derobert, thx for your reply. it's made of 18/10 stainless steel. It's about 5-6 yrs old. I'll try to post a picture of the dots when i get a chance to take one. I'm not Ansel Adams so no guarantees I'll be able to get a good shot. =) – Classified Apr 17 '14 at 18:19
  • 1
    That may just be mineral build up... I'd try cleaning with (distilled white) vinegar or dilute citric acid. – derobert Apr 17 '14 at 18:19
  • @derobert, just attached the picture. hopefully it shows the problem clearly. thanks again for your comments and help. – Classified Apr 18 '14 at 16:11
  • 1
    Those are so minor, I won't even worry about them. – SAJ14SAJ Apr 18 '14 at 16:38

Those are mineral deposits. You can remove them with either vinegar or citric acid. Personally, I use citric acid:

  1. Fill the kettle with some water.
  2. Heat the water (doesn't need to boil).
  3. Sprinkle a little citric acid in (use food-grade, also sometimes called "sour salt").
  4. Let it sit for a few minutes.
  5. The spots should vanish.
  6. Dump the water out, rinse it a few times.

Works about the same with distilled vinegar, except you'll want some ventilation when you heat the vinegar (again, not to a boil), as the acetic acid vaporizes.

The heating isn't actually required for either approach, it just speeds the process up.


You aren't going to get mold on it unless you've been using your kettle for something other than boiling water. Mold needs something to eat, there's nothing in a kettle for it to feed on.

The dots you see are likely discoloration due to mineral deposits in your water. You'll probably find that the dots are occurring where the air bubbles form as the water heats. I'm not sure what the exact mechanism is but it's a combination of the heat, minerals, and the air bubbles which causes the dots to form. I don't think you can get rid of them although you could try to de-scale it. In any case it's perfectly safe to use the kettle.

  • 1
    Once any microdeposit is formed, it becomes a ... whatever the opposite of a nucleation point is, so bubbles are more likely to form there. Then, when those bubbles do form, their mineral deposit will be left in the same place, and the dot will grow. – SAJ14SAJ Apr 18 '14 at 12:38
  • I think those are still nucleation sites... en.wikipedia.org/wiki/Boiling – vwiggins Apr 22 '14 at 9:54

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.