How to clean a concrete driveway

Updated 2026-10-06

You can clean a concrete driveway yourself with a stiff broom, the right cleaner for each kind of mark and plenty of patience. Kill the growth first, scrub or rinse second, and treat stains on their own. A hired machine is optional, and the hardest part is often doing it without damage. If you would rather hand it over, we arrange water blasting for North Shore driveways.

What's the best way to clean concrete?

The best way is chemistry first, force second. Sweep the drive, apply a moss and algae treatment on a dry day with no rain forecast, and give it time to kill the growth. Then scrub with a stiff broom and rinse with a garden hose, or clean with a pressure washer at a sensible distance. Deal with oil and rust as separate spot jobs.

Start by looking at what you actually have. Green film is algae. Soft green cushions in the cracks and along the edges are moss. Grey-white crusts and hard black dots are usually lichen. Dark patches where the car sits are oil, and orange marks are rust from furniture legs, bikes or fertiliser pellets. Each one responds to something different.

1. Clear the drive: cars, bins and pots off, and leaves swept up.
2. Block or cover the drains at the bottom of the drive, and plan where the water will go.
3. Apply a moss and algae treatment to the whole surface, following the label for dilution.
4. Leave it to work. Some spray-and-leave treatments do most of the job themselves over weeks of weather; others are scrubbed off the same day.
5. Scrub with a stiff deck broom and rinse, or move on to a pressure washer if you have one.
6. Spot-treat whatever marks are left.

This order matters because roots left in the pores grow straight back. Concrete is full of tiny holes, and moss and lichen anchor themselves in them.

How do you get concrete white again?

Mostly by removing what has grown on it. Grey and black concrete is usually covered in algae, lichen and grime, and a treatment followed by a scrub or surface clean brings back much of the original colour. Bleach-type cleaners whiten quickly but are harsh on plants and drains. Oxygen-type cleaners are gentler and slower. Truly old concrete brightens, but rarely looks brand new.

Cleaners for concrete fall into a few broad types, and it helps to know which you are buying:

• Bleach-type cleaners (sodium hypochlorite): fast-acting on algae and mould stains. They are tough on garden plants and lawn, corrode metal, and must be kept well away from stormwater drains. Rinse thoroughly and protect the edges of garden beds.
• Oxygen-type cleaners (sodium percarbonate): a powder that releases hydrogen peroxide and soda ash when dissolved in water. Gentler on surroundings, good for general grime and organic staining, and slower to work.
• Moss and algae killers: usually quaternary ammonium based, designed to kill growth and keep working for weeks or months on the surface.
• Alkaline concrete cleaners and degreasers: lift general dirt, tyre marks and fresh oil.

Strong acid washes come up in a lot of online advice. They are corrosive, they eat into the surface of the concrete itself, and they need proper protective gear and neutralising. We leave them out of DIY cleaning and suggest you do too.

How do you get oil and rust stains off concrete?

Treat them on their own and be patient. Fresh oil lifts with a degreaser or a biological oil remover that uses bacteria to break it down. Old, deep oil responds best to a poultice cleaner that dries on the stain and draws oil out of the pores. Rust needs a dedicated stain remover, usually acid-based. Water pressure alone tends to spread oil and does nothing for rust.

For oil, soak up anything still wet with sawdust, cat litter or a rag first. Scrub a degreaser into the stain with a stiff brush, leave it for the time on the label, and rinse into a bucket or onto lawn, not into the drain. A poultice works more slowly: you pour or spread it on, let it dry out over several hours, then sweep up the powder with the oil in it. Repeat if the mark is still dark.

For rust, use a product sold specifically for rust or iron stains on concrete, test it on a hidden spot, wear gloves and eye protection, and rinse well. The same type of remover often shifts tannin stains left by leaves or hardwood furniture.

Set your expectations. An oil stain that has been baking into a driveway for years will usually lighten rather than disappear completely.

Should you hire a water blaster for your driveway?

You can, but a hired or home water blaster is the easiest way to damage a driveway. Held too close, or used with a narrow jet, it cuts into the surface, exposes the stones and leaves light and dark stripes where passes overlapped unevenly. A wide fan tip, a steady distance and a surface cleaner attachment reduce the risk. For a big drive, a professional rig is quicker and more even.

The striping, sometimes called zebra striping, happens because a wand cleans a narrow line at a time. Every slight change in distance or speed shows once the concrete dries. A rotary surface cleaner, the round hood with spinning jets that professionals use, cleans a wide, even circle and avoids most of it.

If you do it yourself:

• use a wide fan tip, never a pencil or zero-degree jet, which can gouge concrete and cause a serious injury
• start well back from the surface and move closer only as far as you need to
• keep the wand moving at a steady pace and overlap each pass by about half
• go gently on exposed aggregate, where the stones can loosen, and on paver joints, where the sand washes out
• wear closed shoes and eye protection, and keep children and pets inside

Never take a water blaster onto a roof. Apart from the fall risk, older roofs may contain asbestos, which must never be water blasted.

How do you keep driveway run-off out of the stormwater?

Plan where the water will go before you start. Cover or block the drains on and below the drive, use rolled towels, sandbags or sand socks to steer water onto lawn or garden, and mop up anything that pools by a drain. The council rule applies to homeowners too: no wash water, sediment or detergent, even a biodegradable one, should reach a stormwater drain.

Stormwater is not treated like sewage. What goes into a grate on your driveway or the street heads, as the council puts it, straight to streams, rivers and the sea. Auckland Council's guide to pressure washing and water blasting explains that landowners are responsible for work on their land, and it lists infringement fines for pollution.

Small things that help on a DIY job:

• work downhill toward the lawn rather than toward the street
• don't apply moss treatments when rain is forecast
• sweep up the sludge left after scrubbing and put it in the rubbish rather than hosing it away

Should you seal a driveway after cleaning?

It is worth considering once the driveway is clean and completely dry. A sealer slows down how quickly oil, water and growth soak back into the concrete, which makes the next clean easier. Penetrating sealers keep a natural look and grip. Film-forming sealers give more colour and some sheen, but can wear in tyre paths and get slippery when wet.

Leave the concrete to dry for as long as the sealer label says, often a day or two of fine weather after cleaning. Apply thin, even coats, keep cars off it for the time given, and pick a product with a grip additive for sloping North Shore drives. If your drive is coloured or exposed aggregate, test a corner first, because some sealers darken the surface more than expected.