Driveway pressure cleaning: how to clean concrete properly

A driveway is the biggest single surface most people see when they look at your house, and it is the first thing that gives away a tired-looking property. The good news is that concrete is one of the few surfaces that genuinely responds to high pressure — the trick is using the right tool, the right technique and the right sequence. Here's how a driveway clean is actually done.

Why Canberra driveways go grey, green and black

Three things conspire against concrete in the ACT:

• Cold, damp winters. Long shaded periods and frost keep moisture sitting on the surface, and that's exactly what black mould, algae and lichen need to colonise concrete.
• Deciduous street trees. Many of the older Canberra suburbs are lined with oaks, elms and liquidambars. Wet leaf litter left on concrete leaches tannin and leaves brown shadow stains that no amount of hosing shifts.
• Dust and clay. Dry summers drive fine dust into the surface pores, and it greys off the whole slab evenly — which is why people often don't realise how dirty a driveway is until half of it has been cleaned.

None of that is "dirt" in the sweep-it-off sense. It's biological growth and staining that has bonded to the top layer of the concrete, and it needs water force plus chemistry to remove.

What you actually need

Item	Why it matters
3000–4000 PSI machine, 12–15+ L/min	Pressure breaks the bond, flow rate carries the debris away. Flow is the half most people ignore.
Rotary surface cleaner	Two spinning jets under a shroud. Cleans in an even sweep with no stripes, roughly 4–6× faster than a wand.
25° or 40° fan tip	For edges, joints and detailing. Never use a 0° needle jet on concrete.
Sodium hypochlorite or a dedicated concrete cleaner	Kills the mould and algae at the root so it stays clean months longer.
Degreaser	Pre-treats oil drips under the car so they don't just get spread around.

Step by step: cleaning a concrete driveway

1. Clear and sweep. Move cars, pots and bins. Sweep off loose leaf litter — blasting wet leaves just paints tannin further across the slab.
2. Spot-treat the stains first. Degreaser on oil patches, an oxalic-based rust remover on any orange bore-water or metal staining. Give each product its dwell time. Our guides on oil stains and rust, efflorescence and tyre marks go deeper on each.
3. Pre-wet and apply the cleaning solution. Wet the concrete, then apply your mould-killing solution across the whole slab and let it dwell 10–15 minutes. Don't let it dry out in the sun — mist it again if needed.
4. Protect the surroundings. Pre-wet garden beds and lawn edges so any runoff is diluted, and cover anything sensitive. Keep chemical runoff out of the stormwater drain.
5. Run the surface cleaner in overlapping passes. Move at a slow, steady walking pace with each pass overlapping the last by about a third. Consistent speed is what prevents stripes.
6. Detail the edges. Switch to the fan tip for the perimeter, the join against the garage, expansion joints and around drains — the bits the round surface cleaner can't reach.
7. Final rinse. Rinse the whole slab in one direction to flush residue off, and rinse down any adjacent walls or garage doors so you don't leave a dirty splash line.

Pressure by surface type

Surface	Approach
Plain broom-finish concrete	Full pressure, surface cleaner
Exposed aggregate	Reduced pressure, wide fan, chemistry-led
Stencil-crete / coloured or sealed concrete	Low pressure only — pressure strips the colour and sealer
Brick or concrete pavers	Full pressure, then re-sand the joints
Asphalt / bitumen driveway	Low pressure — high pressure lifts the aggregate and cuts holes
Old, spalling or crumbling concrete	Low pressure — pressure will accelerate the break-up

The four mistakes that give a DIY driveway away

• Zebra stripes. Caused by waving a wand in arcs instead of walking a surface cleaner in straight, overlapping lines. Once the clean and dirty bands are that distinct, the only fix is doing the whole slab again properly.
• Wand marks and etching. A turbo nozzle parked in one place carves a visible scar into the cement paste. It's permanent.
• Cleaning without chemistry. Water alone removes the visible layer but leaves the mould roots behind, so the green is back within months. Killing it first is what makes the clean last.
• Stopping at the driveway. A gleaming driveway next to a grey path and a mouldy garage wall just highlights the contrast. Do the connected surfaces at the same time — it's also cheaper as one visit.

What it costs in Canberra

Driveway and concrete cleaning typically runs $150–$450, starting from around $149. The variables are size, condition and access — a steep block or a driveway that hasn't been touched in ten years takes more passes and more pre-treatment. Bundling the driveway with your other concrete surfaces or a house soft-wash is materially cheaper than booking separate visits, because most of the cost is getting the gear on site.

How often, and what to do afterwards

Plan on every 12–24 months, or annually if your driveway is shaded or under trees. Two things stretch that out: clearing leaf litter promptly through autumn instead of letting it sit and stain, and sealing the concrete once it's clean and fully dry. A sealed driveway sheds oil and tannin instead of drinking them in, and the next clean takes half the time.

FAQs

How much does it cost to pressure wash a driveway in Canberra?

Most residential driveways land between $150 and $450, starting from around $149 for a single garage apron or short drive. Price is driven by square metreage, how badly stained it is, and access. A long double driveway with heavy black mould and oil sits at the upper end. See our Canberra pressure cleaning cost guide for the full breakdown.

What PSI do you need to clean a driveway?

For plain concrete, 3000–4000 PSI paired with a flow rate of at least 12–15 litres per minute is the professional standard, and it should be delivered through a rotary surface cleaner rather than a bare wand. A domestic 1800–2200 PSI machine will still clean concrete, it just takes far longer and struggles with ingrained mould and oil.

Will pressure washing damage my concrete driveway?

Sound concrete handles high pressure well. Damage happens when a narrow or turbo nozzle is held too close, too long, or in one spot — that etches the surface and leaves permanent wand marks. Exposed aggregate, decorative stencil-crete and old, flaking concrete need lower pressure and a wider fan.

How often should a driveway be pressure cleaned?

Every 12 to 24 months suits most Canberra homes. Shaded, south-facing or tree-lined driveways go green faster and are usually better on an annual clean. Cleaning regularly is quicker and cheaper than letting a decade of mould and tannin build up.

Do I need to seal my driveway after cleaning?

You don't have to, but sealing a freshly cleaned driveway makes future cleans much easier and helps resist oil and tannin staining. Concrete must be completely dry — usually 24 to 48 hours after washing — before any sealer goes down.

Can you pressure wash exposed aggregate?

Yes, but with care. Exposed aggregate relies on the cement matrix holding the stones in place, so excessive pressure dislodges pebbles permanently. Use a wide fan tip, keep the nozzle well back, and let a cleaning solution do most of the work.