How to Remove Dark Water Stains in Wood

Wood floors and furniture are a classic addition to any home. Unfortunately, water cam damage wood floors and furniture, causing an unsightly dark stain that can be difficult to get rid of. Tap water is especially bad when it comes to leaving a dark water stain, because it contains iron as a trace mineral, which reacts with the natural tannic acid in the wood and creates a black mark. Two effective methods help remove the black water stain from the wood, restoring it to its natural beauty.

Scrub the dark water stain with steel wool and a wood floor cleaner.

Pour white vinegar directly onto the stained area and leave for three to four minutes.

Sand the area with a fine sandpaper such as 180-grit if the dark water stain remains. Follow the grain of the wood and sand at least 3 inches around the diameter of the stain.

Re-wax and polish the wood with the same type of wax used on the rest of the floor or furniture piece.

Mix together 2 to 4 tbsp of oxalic acid crystals (depending on the severity of the stain) and a pint of hot water in a heat-resistant glass. Oxalic acid is a bleach so you will effectively be bleaching the stain from the wood.

Dip a clean cloth or sponge in the mixture and apply the mixture to the entire area of the wood. Do not apply to the stain only; this can result in uneven bleaching.

Leave the oxalic acid solution to work for 10 to 20 minutes. If the stain remains, apply more solution to the stained area only.

Mix together 1 tbspclear ammonia and 1 qt. water. Apply mixture to entire surface to neutralise the oxalic acid and stop bleaching. Rinse the surface with clean water and dry thoroughly.

Sand down any raised grain caused by the water stain using fine grain sandpaper.


The white vinegar method works best on less severe black water stains. The oxalic acid method works well on deeper or older stains. If you are unsure which method is best, try the white vinegar method first, and move on to oxalic acid if the vinegar does not work.


Commercial bleaches like oxalic acid are dangerous to the skin and eyes. Wear gloves and protective goggles and treat the wood in a well-ventilated area.

Things You'll Need

  • Steel wool
  • Wood floor cleaner
  • White vinegar
  • 180-grit sandpaper
  • Wood wax
  • Oxalic acid crystals
  • Heat-resistant glass
  • Water
  • Clean cloth or sponge
  • Ammonia
  • Protective gloves and goggles
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About the Author

Writing since 2009, Catherine Hiles is a British writer currently living Stateside. Her articles appear on websites covering topics in animal health and training, lifestyle and more. She has a Bachelor of Arts in communications from the University of Chester in the United Kingdom.