The Easy Way to Get Mold Off Grout

So...I have this embarrassing problem. The grout in one of our bathrooms is perpetually moldy. It's not for lack of trying to clean it, though! For years, I've struggled to get that grout mold-free, using all kinds of different cleaners...but the mold always won the war.

Then I (finally!) realized the problem wasn't a matter of finding the right cleaner. After all, the best killer of mold is ordinary bleach. The problem was keeping the cleaner on the mold long enough for the bleach to do its work. As I learned last weekend, the solution is so simple, I should have thought of it years ago! You see, all I needed to do was thicken the bleach so it could stick to the grout for a little while.

Here's how I accomplished that.

1. Pour a little household bleach into a glass bowl.
Mold on my grout. Gross!

2. Sprinkle in some baking soda (which won't react negatively with the bleach, making it unsafe).

3. Using an old brush (I used one of the bazillion water color brushes my kids have), mix together these ingredients until you have a paste. If the mixture is too watery and runny, add a little more baking soda. If it's so thick you can't mix it, add a bit more bleach.
Mix the bleach and water to create a paste.
4. Brush the paste onto the grout. Be sure to cover the grout thickly, so you can't see any mold. If there's a large area to cover, work one section at a time.

5. Cover the paste with plastic wrap. This helps keep the paste moist - and actively killing mold - longer.
Cover paste with plastic wrap.
6. Leave in place for a couple of hours, then, in one of the most moldy areas, remove a little of the plastic and wipe the paste away. If the grout looks mold-free, remove all the plastic and rinse everything down, removing the paste. If there's still some mold, cover the test area with plastic again and wait another couple of hours before removing all the plastic and bleach/baking soda paste.




  1. thank you so much for sharing this effective method. I will definitely use it. :)

  2. I used this today and I worked like a charm. We were to the point we thought we needed to replace the grout. Thank you !!!

  3. I have grey grout. Can i still use this treatment?

  4. I'm sorry I didn't see your question until today! I don't have personal experience with colored grout, but from what I've read, you shouldn't use bleach on it.

    1. How then should you treat grout (or silicone) that has mould and looks awful. ie edging around baths or in my home silicone edging around PC windows? I like concept proverbs 31.
      Thanking you in anticipation Howard

  5. I would try oxygen bleach, which is color safe. But first, I'd probably just mix baking soda and water into a paste, apply, and scrub. If those things don't work, I'd buy a commercial grout cleaner. Good luck!

  6. Thank you so much. It works. Wow!