How To Clean Stained Cement or Concrete
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Don’t let the lack of a pressure washer keep you from cleaning your stained cement — just use these household ingredients and some elbow grease.
Cleaning a stained cement or concrete floor patio or floor isn’t a quick task, but it’s not difficult, even if you don’t have a pressure washer. The best cleaner depends on the type of mess, but most cement stains come up with household ingredients if you’re willing to work at it.
General Cement Cleaning
- Sweep the surface with a push broom to remove debris and loose dirt.
- In a bucket, combine 1/2 cup baking soda, 1 gallon of hot water, and 1 teaspoon of grease-cutting liquid dish soap. Use a push broom or stiff brush to spread this around and scrub dirty spots. Rinse, and let it dry.
- For lingering stains, rewet the surface and sprinkle it lightly with Oxiclean. (Or you can make your own oxygen bleach.) This won’t harm your lawn or plants lining your driveway, unlike chlorine bleach. Again, use the broom’s bristles to scrub the area, then wait for 10-15 minutes.
- Rinse the surface with a garden hose and your broom. Let both fully air dry.
Mold, Mildew, or Moss Stains
Sweeping alone isn’t enough to remove mold, moss, or cement sidewalks, patios, or steps. To clean mold stains on your cement, you must kill the spores or plant material causing the problem.
- Spray the stain with equal parts of distilled white vinegar and hot water.
- Using the push broom, scrub the area well after spraying.
- Rinse with a bucket of fresh water and let the area completely dry.
- If mold or mildew stains persist after drying, use a cleaning solution of 1/4 cup oxygenated bleach mixed into 1 gallon of hot water. Let this sit for 15-30 minutes, then rinse and dry the surface.
Greasy or Oily Stains
Oil leaks from cars, lawnmowers, or other equipment can leave a slippery stain on your garage floor or driveway. Since cement is porous, you may find the oily mess has worked its way below the surface to leave a deep stain. You can still get them out with some patience — no power-washer required.
- Sprinkle a 1/2-inch thick layer of cornstarch or clay cat litter on the stain to soak it up. Put a box over it if needed to keep the powder from blowing away.
- Allow the powder to remain in place for 24 hours to lift the oil. Check it a few times and apply more if you see the top layer starting to show grease. After a full day, sweep up the mess and discard it.
- Next, combine 1 quart of very hot water and 1 teaspoon of liquid dish soap in a bucket. Dawn Original or Powerwash are both excellent degreasers for this. Or you can try adding 1/4 cup of Pine-Sol but avoid using pine oil products if you have pets.
- Apply the mixture to the area and scrub it with a brush or broom. Rinse well with hot water, then let it air dry.
You can also use a mop, bucket of warm water, and trisodium phosphate (TSP) to clean concrete floors and remove oily, tough stains. Be sure to follow all safety precautions on the package, however, since TSP is very alkaline and can cause burns and skin irritation.
Rust Stains
If the rust stain on your cement is fairly fresh, cleaning it with straight white vinegar and a stiff, non-metal brush may be enough to remove it. Rinse well with fresh water afterward, though, since undiluted vinegar can etch cement over time.
For larger or older rust stains, get the area damp and then sprinkle it with a product containing oxalic acid. (I use Bar Keeper’s Friend.) This all-natural acid is mild enough that it won’t etch your cement but is strong enough to dissolve rust. Scrub the spot with a stiff, non-metal brush, rinse thoroughly, and repeat until the stain is gone.
Tips to Prevent Cement Stains
Cleaning your outdoor areas is a year-round task. Sweep cement patios, steps, and sidewalks weekly during warm weather and at least once a month during winter. Sweep your garage at least once a month, too. Clean spills on concrete when you see them and use fans to dry indoor cement areas any time they get wet. Routine cleaning of cement and concrete areas is ultimately the easiest way to prevent stains.
Apply a sealant to your garage floor. If you plan to sell your home in the next year or two, this step can really impress buyers. (Here are more cleaning tips to protect your home’s value.) DIY sealants need to be reapplied every 2 to 3 years. Professional, penetrating concrete sealants can last as long as 20 years and often carry a transferrable warranty.
Use oil drip mats in parking areas. Look for a slip-proof one that’s easy to clean and it will keep oil or other leaking car fluids from damaging your floor. (We use this one.)
Use rugs or mats beneath patio furniture to catch spills and prevent rust spots. Choose a rug specifically designed for outdoor use so water doesn’t damage it. Outdoor rugs and mats won’t trap water beneath them that could lead to mold or mildew growing on your patio.
Don’t put flower pots directly onto your patio or front step. Use drip trays beneath planters so runoff and soil don’t cause stains. Be sure to empty those trays after heavy rains so they don’t attract mosquitoes.
Divert rainwater. Use downspout extensions to divert downspouts so they drain onto your lawn, away from your foundation and concrete surfaces.
Rake leaves. Clear away leaves and other debris after storms or during the fall season. Letting autumn leaves collect on your patio can trap moisture and cause mold and mildew stains.
Help, I have a stain in my basement cement from soda that wasn’t found for a while that stained into the cement and its black. What is a safe way to try to get rid of it.. TIA
I’d try oxygen bleach and water to start.
I have a stamped concrete patio and just power washed it so that I can apply a wet look sealer. After power washing the patio, the areas under where the table and grill were located have a different and darker look to them (concrete has a stamped dark tone originally). Could this discoloration just be due to less wear and tear from sun and weather elements? Or should I look into a cleaning agent for those areas? Thanks for any response that you can’t provide.
Since your stamped concrete is dark-toned, my guess is that the other areas have faded with exposure to the elements. Probably not much you can do about that, but you might want to ask a concrete professional.
I have white cauking smears on my cement door threshold and surrounding brick from a bad installation. How can I remove these stains?
Hi Gerry,
Mineral spirits and a good scrub with a stiff brush should do it. You can also find caulk residue removers at most hardware stores.
I never would have thought of using baby powder to clean up oil stains in my garage. I had heard about cat litter, but it never really did all that much, probably because I didn’t grind it up first. Anyway, thanks for the tip hopefully I can get the oil stains up quickly so that I can reseal the floor.
Here is a tip. If using a push broom with the cat litter, flip it over and grind the litter in with the wooden side of the broom first. It will work great to grind up the litter and force it into the stain.
That’s a helpful tip, Dale. Thank you for sharing!