Why does my tile floor produce black water when we clean it?


We purchased a condo that has an 18 x 18 tile floor in the kitchen. It was put in about 10 years ago. The tile looks perfectly fine. No stains, no spots, no obvious dirt. It is kind of a rustic rust/brown/beige color. We put in new carpet in the dining room, but the carpet always looks dirty in the area right outside the kitchen (tile) into the dining room (carpet). I had the tile floor professionally cleaned and the water was black! They have re-cleaned it multiple times and the water continues to be almost black. There is no obvious difference in the tile after the cleaning. What could be the cause? Is it possible the tile is dissolving or something? The floor guy did not think it could be sealed because it wasn't porous enough. There is obviously something wrong or when cleaned the water would not continue to be black. Please Help! My floor is not dirty but continues to produce black water when cleaned.


ANSWER - The black stain in the water has to be coming from somewhere and caused by something.  The question is where and what?

The question is what type of tile do you have?  There are many types of ceramic tiles.  There are glazed tiles which have an impervious surface or porcelain tiles that are impervious in the body of the tile, there are vitreous tiles that have up to 3% absorption, semi-vitreous tiles that have up to 7% absorption, and there are non-vitreous tiles that can have up to 20% absorption.

There are rustic non-vitreous tiles that can be stained and sealed.  Depending on the type of stain and sealer it could bleed color.  The cementitious grout between the tiles is absorbing so it could hold a stain and bleed color.   So unless we know exactly what type of tile, we can't give an exact conclusion.

I would take a neutral based detergent and apply a solution to the floor and let it soak in.  They scrub it with a scrub brush on an extended handle.  Then get a wet and dry vacuum to pick up the dirty water.  Then I would rinse the floor with clean water a couple of times and each time I would use the wet and dry vacuum to pick up the water.  Then take a clean white towel and rub it on the clean tile floor and see if it picks up a stain.  If it does, then the tile is the source of the stain.

Then you can apply a penetrating type of sealer over the tile even if the tile doesn't absorb much, but you have to immediately buff the floor dry with a clean lint free cloth.  The sealer might keep the tile from continuing to bleed.  You may have to re-seal every 6 months to a year depending on what kind of traffic you floor is subjected to.   Be sure to test this method out first in an inconspicuous spot to make sure it works to your satisfaction before you apply it to the entire floor.

You can go to our website to the Resource Directory to the Sealer and Cleaner section for a list of manufacturers who you can contact for the cleaner and sealer products you decide to use.  https://ctasc.com/category/resources/cleaners-sealers/

8 thoughts on “Why does my tile floor produce black water when we clean it?

  1. Christina Hurni says:

    Is there an answer to this because my tile comes out black and I clean it all the time and I thought it was furnace soot but it only happens in the kitchen. I’m at my wits end.

    • Donato Pompo says:

      If the tile only gets dirty in the kitchen and you don’t have this problem on this tile in other areas of your home, then we can assume that it is coming from the kitchen.

      Some grouts in the tile grout joints have been know to bleed, but that isn’t common and I haven’t seen that condition in years. If you have a floor furnace register then maybe the flow of air is such that it leaves residuals in the kitchen. If you do have a floor furnace then check the filer at the register and make sure it is clean and has been replaced recently.

      Kitchens tend to get a lot of traffic. If you have a Kitchen door to the outside that can track dirt in. You can put walk-off mats down to try to minimize this if that is the case.

      It is just a process of elimination to narrow down the cause of the dirty conditions. If it was practical we could test the residue on the tile in a testing laboratory to determine its source.

      • Christina Hurni says:

        Thanks for answering so quick. I put white paper towels on the kitchen and hall register and those are the only areas with tile and got no black on them over night with the heat running and they aren’t particular dirty. The grout is the same light tan color as the tile….seems clean when I wipe one day after washing the floor but I wash the floor once a week and we only where our socks at home. It only started being so black after one week of washing in the last few months and we have had the tile floor for about 7 years. I am most fearful about soot so am really hoping it is not that and I don’t have a furnace service until July.

        • Donato Pompo says:

          if it only started since you started washing the floor, then change the type of cleaner that you are using. Don’t use a mop that just spreads dirt around. Use a scrub brush on an extended handle and then use a wet vacuum to pick up the dirt water. Then rinse with clean water and again pick that up with the wet vacuum.

  2. Sue says:

    I have the same issue. Our house is spotless and nothing else is dirty or has film. However when we wash the tile floors the water is black. I am thinking it needs to be sealed.

    • Donato Pompo says:

      If you are using a mop you can’t get the floor entirely clean.

      Don’t use a mop that just spreads dirt around. Use a scrub brush on an extended handle and then use a wet vacuum to pick up the dirt water. Then rinse with clean water and again pick that up with the wet vacuum.

    • Donato Pompo says:

      Normally black mold is on the surface in an area that stays wet from shower use or humidity. It normally comes clean easily.

      The situation above where they say they clean the floor and they keep getting dirty water is more likely from not cleaning properly to remove all of the residual dirt. Tile is an inorganic material so it isn’t going degrade from cleaning.

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