Made some tea using a drip style coffee maker by placing tea bag where coffee would normally go, namely on the standard fibrous (paper) coffee filter. After the tea has been on the warmer for a while, it develops dregs. Actually it's not so much dregs as particles that sometimes sink to the bottom and sometimes float and stick to the side of the carafe. The tea also develops an oil slick on top. It makes for some nasty looking stuff which sticks to the sides of my cup as well. I fail to understand how these dregs got through the coffee filter in the first place. I pour it back through the filter, but it then drips slowly, as if the filter were clogged. Any clues as to what is happening here? It has happened with 3 different kinds of tea (all in bags).

  • 2
    Why are you putting a tea bag in a coffeemaker?
    – Catija
    Commented Apr 5, 2018 at 18:03
  • 5
    @Catija in fairness I used to do this in college (a coffeemaker being one of the few permissible devices) but I'd just hang the tea bags in the water carafe to steep. Sounds like the coffeemaker is dirty and needs a good cleaning.
    – logophobe
    Commented Apr 5, 2018 at 18:19
  • 1
    @logophobe Hmmm... yeah. Sounds more like coffee residue than tea.
    – Catija
    Commented Apr 5, 2018 at 18:26
  • 2
    Don't know about the particles, but an oil slick that develops on top of tea is normal. I guess tea must contain oils (probably carrying some of the aroma ?), because if a cup of cold tea is left sitting around, it often gets a very thin rainbow layer of oil on top. I have seen it before.
    – Lorel C.
    Commented Apr 6, 2018 at 4:18

1 Answer 1


Regarding the oil film, this is called 'tea scum' and it's completely safe.

The filter gets clogged because the tea particles are small and fill up the spaces in the filter. Then it gets in touch with water and expand. At this point, the filer will get clogged.

There's generally no reason to use a coffee filter as the tea bag itself functions as a filter.

  • Machine is clean, so not coffee residue. Using coffee filter in addition to tea bag b/c of the clumping dregs about which I am asking. Figured maybe the bags were leaking. Lastly, making tea in this fashion, b/c I get busy and forget about tea bag steeping if I just put it in the carafe with hot water.
    – Vince
    Commented Apr 11, 2018 at 8:14

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

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