The Best Way to Clean a Patio or Block Paving (Without Wrecking the Joints)

Sweep it, treat the growth, then wash at medium pressure with the lance held at an angle and about a foot off the surface. Never point a turbo nozzle straight down at block paving, because that fires the jointing sand out and the blocks start to shift. Then re-sand the joints. That last step is the one almost everybody skips, and it's the one that decides whether the job lasts.

There's also something specific to this summer that changes how you go about it in London, so let's start there.

First, the hosepipe ban

If you're on Thames Water, you currently can't jet wash your own patio. The Temporary Use Ban came into force "at 00.01 BST on Thursday 23 July 2026" and covers "cleaning private cars, patios, paths, driveways or windows" with a hosepipe, as set out in their announcement. Buckets and watering cans are still fine. Breaching a ban can carry a fine.

Here's the part most people miss. The restriction is on domestic use. Thames Water's own hosepipe ban FAQs state that "businesses can continue to use hosepipes when providing services to customers, including: cleaning vehicles, cleaning boats, cleaning windows and outside walls, cleaning paths, patios and other outdoor surfaces", and that "commercial services for customers can still be done using a hose or jet washer".

So the work can still be done, it just can't be done by you with your own hose while the ban is on. If you're on the Hertfordshire side of our patch, check your own supplier's restrictions before you start, because the rules and the dates differ by company.

Start with what the paving is made of

Every mistake we get called out to fix comes from skipping this step.

• Block paving. Held together by kiln-dried sand in the joints. Blast the sand out and the blocks loosen, then they rock, then they sink. This is the most commonly damaged surface in the country.
• Concrete slabs. Tough. Will take a proper wash, though old slabs can spall if you sit in one spot.
• Indian sandstone. Porous and soft. High pressure pits the face and it never looks right again.
• Porcelain. Hard-wearing and low maintenance, but the grout joints are unforgiving and easy to blow out.
• Natural stone, York stone, limestone. Soft, expensive, and best treated chemically rather than with pressure.
• Decking. Timber fibres lift and furr up under pressure. Always go with the grain, always low.
• Resin bound. Never use high pressure. It lifts the aggregate off the base and the repair is a full section.

If you're not sure, test a patch somewhere nobody looks. Behind the shed, under where the table sits.

The right way to pressure wash

Marshalls, who make a good share of the paving in British gardens, give clear guidance in their own block paving cleaning advice. Their instruction is that "the pressure washer should be angled at 30° and sprayed diagonally on a medium pressure", and they warn that "not adhering to this advice may mark the surface of some paving materials and break up the jointing material, resulting in the need to re-sand".

In practice:

1. Sweep first, properly. Loose grit under a jet becomes a scouring agent. Marshalls' own first step is to clear the area "using a stiff broom".
2. Pull the weeds by hand before you start. Washing them just spreads seed into the joints.
3. Treat the growth and let it work. Algae and moss need killing, not blasting. A biocide left to dwell does more than an hour with a lance.
4. Set medium pressure, wide fan. No turbo nozzles on jointed surfaces, ever.
5. Hold the lance at roughly 30 degrees, a foot off the ground, and work diagonally across the blocks rather than along the joint lines.
6. Keep moving in overlapping passes. Stopping burns a stripe in, and tiger stripes on a patio are permanent.
7. Work in one direction so dirty water always runs onto ground you haven't cleaned yet.
8. Rinse everything down, including the walls you've splashed and any planting.

Re-sanding: the step everyone skips

Wash block paving and you will remove some jointing sand. That isn't a mistake, it's unavoidable. The mistake is leaving it that way.

Marshalls are direct about it: after washing, "identify areas where the jointing sand has been eroded or displaced, paying particular attention to high-traffic areas", then "use a stiff brush to carefully fill the joints with kiln-dried sand".

Let the surface dry completely first, because damp sand bridges instead of falling into the joint. Brush it in diagonally, then again in the other direction, and top up any joints that settle after the first rain. On a driveway, get the sand back in before cars go back on it. The sand is what stops the blocks from moving under a wheel.

What about bleach and patio cleaners?

Sodium hypochlorite is what most professional treatments are based on, and used at the right dilution it's the most effective thing for organic growth. Used wrongly it kills borders, stains stone and runs into drains.

A few things worth knowing before you buy something in a bottle:

• Acid-based cleaners shift rust and iron staining but will burn limestone and etch some concrete. Test first.
• Anything you apply runs somewhere. Wet the planting down before and after, and keep it off ponds.
• Iron staining is a different problem. Orange spotting on sandstone usually comes from minerals in the stone itself, not from something on top of it, and no amount of pressure will move it.
• A rust-coloured line under a downpipe is a drainage issue. Cleaning it is treating the symptom.

When it's worth calling someone

If it's a small back patio in decent condition, a dry weekend and a hired machine will get you there. Genuinely.

Call someone when the surface is soft or expensive, when the growth is thick and established, when there's oil on a driveway, or when the joints are already washed out and half the blocks are rocking. Also when it's simply large. A double driveway takes far longer than people expect, and hired machines rarely have the flow rate to make it quick.

We handle patios, block paving and driveways across North London and the Hertfordshire borders as a one-off job, with re-sanding included where it's needed rather than charged as an extra. Where the surface is too delicate for pressure, we use the same low-pressure approach we use on walls, which we explain in our guide to cleaning render safely.

FAQ

Can I jet wash my patio during a hosepipe ban?
Not yourself, if your supplier has a ban in force and you're using mains water through a hose. A business providing the service to customers is treated differently under Thames Water's rules. Check your own supplier before starting.

What pressure should I use on a patio?
Medium, with a wide fan, at roughly 30 degrees and about 12 inches off the surface. Turbo and pencil-jet nozzles are for concrete hardstanding, not for jointed or natural paving.

Do I have to re-sand block paving after cleaning it?
Yes, if any sand has come out, which it will have. The sand is structural. Skip it and the blocks start to move.

How often should a patio be cleaned?
Most London gardens want it once a year, usually spring or early autumn. Shaded and north-facing areas green up faster.

Will cleaning damage my sandstone?
It can, if it's done with high pressure. Sandstone is porous and soft. Chemical treatment with a gentle rinse is the safer route, and it's what we use as standard.

Do you clean driveways as well as patios?
Yes. Driveway pressure washing and patio and decking cleaning are usually quoted together, and both sit under our wider exterior cleaning work.

Getting it done properly

We're a London deep-cleaning company covering North London and the Hertfordshire borders, fully insured with £5 million public liability cover, DBS-checked, and rated 4.9 from 180+ reviews across 500+ jobs.

Send a photo of the patio and rough measurements and we'll price the actual job, including the re-sand. Request a quote, call 07375 104665, or message us on WhatsApp at wa.me/447375104665.