Does anyone know what this red slime/gunk is inside our sink aerator? Besides replacing the aerators, is there anything else we should do?

The red sediment is in the aerator of the sink and one of our bathrooms (but not the other). A few weeks ago, when I was running the the bathroom sink, the water stopped, sputtered, and then turned red/brown before running clear again. When I looked at the aerator I noticed a lot of red gunk trapped there. Today, we noticed the same red gunk in the kitchen sink aerator (but we don't recall a similar issue with red/brown water here). Thanks!

sink aerator with red gunk

  • Is there any new construction in the area? Any water pipe breaks in the area?
    – JACK
    Commented May 25, 2020 at 0:21
  • Hi Jack. Thanks for your response! We live in a large apartment building (200+ units) and they renovate at least a few apartments a month (replacing bathroom and kitchen sinks among other things). When I reported the water running red to building maintenance, he said he'd call the city to see if there was a water main break but never heard back.
    – userL
    Commented May 25, 2020 at 0:25

1 Answer 1


My guess is it's from some of the renovations in the building. They probably changed a sink or two and dislodged some rust from an old pipe. The rust with some pipe dope and clog up the aerators. Just clean the ones you have. This is a very common problem when changing faucets in multi-occupancy buildings.

  • Even just getting an air bubble (which fits the spluttering) in the pipes can free up a lot of gunk that otherwise just sits there.
    – Ecnerwal
    Commented May 25, 2020 at 1:52

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