Start with a broom and water, then move to stronger methods only if needed
The fastest way to clean a concrete patio is to sweep off loose dirt, then rinse with a garden hose. For most patios, this removes the surface layer of dust and debris in under an hour. If water alone leaves stains or dark patches, you have moved into the territory of mold, algae, or set-in dirt—and that is when you choose between a pressure washer, a stiff brush with detergent, or a chemical cleaner, depending on what you are actually looking at and how much elbow work you want to do.
The reason to start straightforward is that concrete is porous and can be damaged by pressure washers if you use too much force or hold the nozzle too close. You also do not need to strip the surface clean every time—seasonal debris and light discoloration are normal and do not harm the concrete itself. Save the heavy cleaning for when stains have set in or mold has started to grow.
Key Takeaways
- A broom and garden hose remove loose dirt and dust from most patios without any chemicals or equipment.
- Pressure washers work fast but can damage concrete if you use more than 3000 PSI or hold the nozzle closer than 12 inches.
- A stiff-bristled brush with a detergent solution removes mold and algae without the risk of pressure damage.
- Concrete sealers protect against future stains and mold but work best on a freshly cleaned surface.
- Stubborn stains like rust or oil may need a concrete-specific cleaner or a professional if they have set for years.
The basic sweep and rinse for seasonal cleaning
Start with a stiff broom—not a soft one—and sweep the entire patio in one direction to push loose dirt, leaves, and pollen toward the edge. This takes 10 to 20 minutes depending on size and how much debris has accumulated. You are not trying to remove stains at this stage; you are just clearing the surface so you can see what you are actually dealing with.
Once the loose material is gone, attach a garden hose with a standard spray nozzle and rinse the patio from one end to the other. Use a medium spray setting—not the jet setting, which can force water into cracks. Let the water run for a minute or two after the visible dirt stops flowing off; this rinses away fine dust that sits in the pores of the concrete. For most patios, this is enough. Let it dry for a few hours and you are done.
If you see dark patches or discoloration after the patio dries, that is mold, algae, or a stain that has set into the concrete. Move to the next method.
Using a pressure washer safely on concrete
A pressure washer removes stubborn dirt and mold much faster than a brush, but concrete can be damaged if you use too much force. The safe range for concrete is 2500 to 3000 PSI (pounds per square inch). Anything above 3500 PSI risks etching the surface or blowing out the top layer. If you are renting a pressure washer, ask the rental company what PSI it delivers and choose one in the safe range.
Hold the nozzle at least 12 inches away from the concrete and keep it moving—do not hold it in one spot. Work in overlapping passes from one end of the patio to the other, the same way you would mow a lawn. Avoid spraying directly at the edges or seams where water can force its way into cracks and weaken the concrete underneath.
Pressure washers are loud and use a lot of water, so check your local water restrictions before you start. If your area has drought conditions or water-use limits, a brush and detergent is the better choice. Also be aware that pressure washing can strip away any existing sealer, so you may need to reapply it after cleaning.
Scrubbing with a brush and detergent for mold and algae
If you want to avoid a pressure washer or do not have access to one, a stiff-bristled brush and a detergent solution removes mold and algae without the risk of concrete damage. Mix a solution of one part household bleach to three parts water in a large bucket. Pour the solution onto a section of the patio and let it sit for 10 to 15 minutes—this gives the bleach time to kill the mold spores.
Scrub the wet area with a stiff brush, using firm circular motions. Work in sections so the solution does not dry out before you scrub. Rinse each section thoroughly with the garden hose before moving to the next one. Bleach can damage plants and grass at the edges, so rinse those areas well or cover them with plastic sheeting before you start.
This method takes longer than a pressure washer—usually 2 to 4 hours for a large patio—but it is gentler on the concrete and uses less water. It also works well for patios with decorative finishes or sealing that you want to preserve.
Treating stubborn stains like rust and oil
Some stains—rust from metal furniture, oil from a grill, or mineral deposits from hard water—do not respond to bleach or pressure washing alone. For these, you need a concrete-specific cleaner designed for the type of stain. Rust stains usually respond to an acidic cleaner; oil stains need a degreaser. Read the label to match the product to your stain type.
explore the cleaner according to the product instructions, which vary widely. Some need to sit for 30 minutes; others work in 5 minutes. Scrub with a brush if the instructions say to, then rinse thoroughly. Test the cleaner on a small, hidden area of the patio first to make sure it does not discolor the concrete or remove any sealer you want to keep.
If a stain has been there for years and does not respond to commercial cleaners, it may have penetrated too deep to remove without professional equipment or grinding. At that point, a concrete contractor can assess whether the stain can be removed or whether sealing is the better option to prevent it from spreading.
explore a sealer to prevent future stains and mold
Once your patio is clean and dry, a concrete sealer creates a protective layer that makes future cleaning easier and slows the growth of mold and algae. Sealers come in two main types: penetrating sealers, which soak into the concrete and protect from within, and film-forming sealers, which sit on top and create a visible shine.
Penetrating sealers are less noticeable but last longer—usually 3 to 5 years. Film-forming sealers look better and are easier to explore, but they wear away faster and need reapplication every 1 to 2 years. Both types require a clean, dry surface, so explore sealer only after you have finished cleaning and let the patio dry completely (usually 24 to 48 hours after washing).
Follow the product instructions for process—most are rolled or sprayed on in thin, even coats. Avoid walking on the patio until it has cured, which can take 24 to 72 hours depending on the product. A sealed patio resists stains better and needs less frequent deep cleaning, though you should still sweep and rinse it seasonally.
When to call a professional for concrete cleaning
Most patios can be cleaned with the methods above, but some situations call for professional help. If your patio has deep structural cracks, if stains have penetrated so far that surface cleaning does not touch them, or if you suspect the concrete itself is damaged, a concrete contractor can assess the problem and recommend repair or replacement if needed.
Professionals also have access to stronger equipment and chemicals that are not available to homeowners, and they know how to use them without damaging the concrete. If you have tried multiple cleaning methods and the stain or mold keeps coming back, that usually signals a moisture or drainage problem underneath the patio—something a professional can diagnose and fix.
Frequently Asked Questions
Can I use vinegar instead of bleach to clean concrete?
Vinegar is weaker than bleach and works better on mineral deposits than on mold or algae. It is safer to use around plants and pets, but you will need to scrub longer and may not get the same results on heavy mold growth. For light cleaning or mineral stains, a 1:1 mix of vinegar and water works; for mold, bleach is more effective.
How often should I clean my concrete patio?
A light sweep and rinse once a month keeps debris from building up. A deeper cleaning with detergent or a pressure washer once or twice a year is usually enough unless your area has heavy mold growth or you live near trees that drop a lot of debris. Sealed patios need less frequent deep cleaning.
Will a pressure washer damage my patio if I use it wrong?
Yes. Pressure above 3500 PSI or holding the nozzle too close can etch the surface or create pitting. If you are not confident with a pressure washer, rent one with a lower PSI or use a brush and detergent instead. The concrete will not be damaged either way.
What is the white powder on my concrete after cleaning?
That is efflorescence—mineral salts that rise to the surface as the concrete dries. It is harmless and usually disappears on its own or washes away with the next rain. If it bothers you, a stiff brush or a commercial efflorescence remover will clear it, but it often returns if moisture is still moving through the concrete.
Do I need to seal my patio after cleaning?
Sealing is optional but helpful if you want to reduce staining and mold growth. It is most effective on a freshly cleaned patio and lasts longer if you keep the surface clean. If your patio is in a shaded, damp area, sealing can slow mold regrowth significantly.