The kitchen faucet in my apartment has been leaking above the counter for years, but every time I complained to management about it nothing happened and it wasn't enough of an annoyance to make me push them since I could just wipe down the counter afterwards. What I didn't realise was that there wasn't a proper seal to stop water running through the faucet fixture and into the exposed ~2" thick MDF on the underside of the counter, at least until there was an unidentifiable lingering odour that made me investigate things thoroughly. Now there's a pretty nasty mould infestation around the whole faucet/sink area.

I've redoubled my efforts to make management actually do something about this, which will remove the source of moisture, but I'm unsure whether I'll be able to get them to take care of the mould properly. I'm concerned that the mould is fully permeating the bulk of the counter and any surface cleaning isn't going to accomplish much.

How much work should I expect to be done to fix this? Is anything less than replacing the whole countertop going to be effective?

  • 2
    If it's black mold, that's a very serious health issue. It can cause long term health issues. And your apt complex should have mold remediation as part of their standard operating procedures. This is info per property managers that I've known. I'd be wary of the cabinets below the leak too. I'd get them to fix it immediately and replace at a minimum the countertop since they were negligent in doing anything about the problem when you initially reported the problem. You need to insist that this get handled properly and escalate it to regional or district managers if they give you any trouble. Commented Aug 29, 2019 at 22:13
  • Give this new information about mold to the landlord and if they still refuse to address the problem then tell them you will need to contact the health department in your town.
    – Alaska Man
    Commented Aug 30, 2019 at 21:19

1 Answer 1


I'd expect you don't have much to worry about. Mould isn't great but it exists outside in the nice fresh air as well. There are some moulds that are quite toxic but you'd need to do air sampling to find out if you have high enough levels of spores to pose any health concerns. Are you sure you even have mould and not algae?

There are cases where you should be more concerned if you are immunocompromised, only have one lung, are an infant or elderly, etc. If you are constantly sick then you might want to spend more time worrying but then I'd hope you are living in a place with no carpet as well. You could buy yourself an air purifier with a hepa filter. A lot of moulds/dust mites/fungus will grow on dust in carpet or even on walls.

Once you have the leak fixed, make sure it gets dry and just seal the mdf underneath with some kind of paint. I'd bet the majority of kitchens/bathrooms have some amount of mould / fungus / algae growing in them. MDF especially the old kind contains formaldehyde resins which off gas vocs but also impede the growth of biological agents like mould.

Do you have a picture of your mould?

The epa states that you should call a professional in if you have more than 10 square feet of mold - which would be a lot. This doesn't sound like that. The worst thing is to have mold growing in your bedroom as that is where you sleep. One other thing I'd recommend is to have a hygrometer in your unit. If the levels are ever over 55% you should buy and run a dehumidifier as you will have mold growing in your carpet / furniture / etc. Some mould under your sink is only a little bit worse than mold in your plumbing pipe which is pretty much guaranteed.

How big of an area of mold are we talking about?

This link talks about the different kind of molds and states that the black mold which is the one to worry about virtually needs constant flowing water https://www.tuck.com/sleep-and-mold/

This is the WHO guidelines for indoor air quality. http://www.euro.who.int/__data/assets/pdf_file/0017/43325/E92645.pdf

This is a good reference for establishing what mold remediation companies consider clean and it seems like unit that have not had flooding issues typically fall into the clean category.


No amount of mold is good for you but since it is ubiquitous you should strive to limit your exposure. Molds live on plants, in the soil, in your carpet, in leaves from trees, you can't really achieve no exposure without living in a bubble. From the description in your case you have a small amount and you have limited exposure given the location. I'd stick with my recommendation, get the faucet leak addressed - maybe they'll decide to replace the counter/sink at the same time (can't hurt to ask). If they don't scrub it out as best you can (wear a 99.9 mask), let it dry and encapsulate the area (an oil based paint would likely do the trick).

This renters guide for mold seems to have decent advice.


  • I disagree. Mold is a long term condition that can affect you and your guests. Even if you wipe the areas clean, it can remain in corners, cracks, etc. which can cause health problems. You definitely need to report it (in writing) and have it removed professionally if it tests positive.
    – Lee Sam
    Commented Aug 29, 2019 at 23:23
  • I've been aggressively spraying it with peroxide mould cleaner at regular intervals to vent my frustration, so it just looks like a wet kind of slimy patch now, but when I first noticed it it definitely looked like mould. Bunch of black/brown patches with some white hairy bits.
    – llama
    Commented Aug 30, 2019 at 1:24
  • 1
    Peroxide is not enough. It will kill on the surface but it will not prevent lingering spores from growing back again. To prevent mold from growing back, you need a solution of trisodium phosphate and sodium carbonate (also known as washing soda / soda ash). It leaves a (human-safe) salt deposit that will prevent fungus from growing there again. There are commercial products available with patented/guaranteed formulas.
    – sleblanc
    Commented Aug 30, 2019 at 3:03
  • @llama Sounds bad...I’d have it tested. Or, you can buy test kits from your local hardware store and do it yourself.
    – Lee Sam
    Commented Aug 30, 2019 at 3:04
  • 1
    You'd get a professional in, pay $500, and end up eating the costs. What kind of test would you get the professional to perform? I'd have a good read of the inspectapedia site, see the questions and answers and take note of how many times they say the "professional provided you with a worthless piece of paper" for your money. Commented Aug 30, 2019 at 7:37

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.