How to Remove Water Stain From Hardwood Floors

What You'll Need
Denatured alcohol
Lint-free cloths
Orbital sander
Mineral spirits
Safety glasses
Dust mask
Paint brush
Finish (polyurethane)

It can be difficult to remove water stains from hardwood floors, but necessary to preserve the wood. This is especially true if the water has been standing for a while. The task is more complex than simply cleaning your floors to remove water stains. The floor has to be refinished once the stain has been removed. However, it is a job any homeowner can undertake.

Step 1: Clearing the Stain

Before you remove water stains from the hardwood floor, you need to clean the floor area. Do this by using denatured alcohol liberally in the area. This will remove all the dust and dirt. Mop up the alcohol before it evaporates with the lint-free cloths until the floor is dry. This prepares the floor for stripping

Step 2: Stripping the Floor

To strip the floor, use the orbital sandpaper with 150 grit sandpaper. Because the water will have soaked fully into the wood, you will need to sand off more than just the surface to remove water stains. Sand down until you see a bright wood color and not just the grey marks of the water stain. Make sure you wear safety glasses and a dust mask when working with an orbital sander and sandpaper.

Now, increase the area you cover with the sander, letting the sander run without any downward pressure. When you’ve created an area of bare wood around the stain, use the cloths and mineral spirits to clean up all the sawdust.

Step 3: Applying a Finish

To complete the job, you’ll need to re-finish the bare wood. Use the polyurethane finish and a brush around 2 inches wide. Begin at one side of the bare wood and use light, even strokes with all of them going in a single direction until you’ve coated all of the area that’s been bared from removing the water stain.

The coat of finish needs to dry. Give it ample time, preferably overnight. The next morning, wearing the dust mask and safety glasses, sand down the finish very lightly using 220 grit sandpaper. Work with your hand, not the orbital sander, for a lighter touch. When you’ve finished, use more mineral spirits to clear up all the sawdust and fine grit. Be extremely thorough with this step.

Step 4: Second Coats

Once it’s completely clean, apply a second coat of the polyurethane finish. Work the same way as you did before, using even strokes and always brushing in a single direction.

Once again, let the finish dry overnight before walking on it. The overall effect when you remove water stains is to effectively create a refinished floor. The new finish should offer a good seal against other spills but will wear down over time allowing standing water to seep through the wood. This method will work effectively where the water stain isn’t too large. To remove water stains that cover a large area, such as from a leaking roof, you should consult a professional since this can be a job that's too big for most homeowners.