Patio Cleaning Service

The thing worth looking at here is not how dirty it was. It is that the patio underneath turned out to be a two-tone chequerboard with a pattern set into the middle of it, and by the time we arrived nobody in the house could have told you that. They had not forgotten in the sense of misremembering. The information had simply stopped being available. You cannot recall a detail you have not been able to see for several years.

That is the part people find hardest to believe about biological colonisation: it does not make a surface patchy, it makes it uniform. A stain has edges. A colonising film does not — it spreads to fill whatever is habitable, and on a patio that is the whole thing. So the buff slabs and the charcoal slabs converged on the same flat grey, the contrast went, and the design went with it. The patio had not been damaged. It had been overwritten.

Which brings up the reason we pre-treat at all, and it is not the reason most people assume. Pressure alone will absolutely make a patio look clean. What it removes is the visible layer, and what it leaves behind is the base — the lichen thallus bedded in the slab face, the algal cells down in the porosity, the spores in the joint. Those are the parts doing the reproducing. Clean without treating and the surface looks excellent in June and familiar again by the following spring.

Here is the part that sounds backwards and is the whole argument. A pre-treated patio needs less pressure, not more. Living, anchored biomass grips; oxidised, dead biomass lets go. Once the chemistry has done the killing, the slabs release at a fraction of the force they would otherwise demand — which means the fine material around the aggregate stays where it is. Used properly, the chemical is not the aggressive step. It is what makes the mechanical step gentle enough to be safe.

There is also a small change to the usual order that makes a large difference. Common practice is to let the solution dwell and then take the rotary cleaner straight over the top of it, which means the machine is driving neat chemical across the slabs and throwing it into the air in front of whoever is holding it. We rinse first and machine second, so the cleaner is working through a diluted solution rather than a concentrated one. Same dwell, same result, considerably less of it airborne and less of it in whatever runs off.

It does have limits, and black spot is where you meet them. That is a crustose lichen, not a mark: a living thing with a body grown into the top millimetre of the slab, which is exactly why scrubbing does nothing and why it survives treatments that flatten everything else. Expect it to need a second application, sometimes a second visit, and expect a scatter of faint ghosts to remain. Anyone quoting on the basis that every spot will vanish has either not looked closely or is not telling you.

Then there is the question almost nobody in this trade will put in writing, which is where the water goes. It depends entirely on the pathway. Rinse onto open ground with no route to a gully or a watercourse, as here, and dilution and soil deal with it. Rinse onto a surface that runs to a street gully and it reaches a brook essentially as it left you, because a surface water drain is not connected to a treatment works. That second case is a pollution offence, which is why the pathway gets worked out before anything is mixed.

Where there is a pathway, the answer is barriers and a vacuum — stop it reaching the gully, recover it, take it away. And then you reach a genuinely unresolved problem the trade tends to talk around, which is that there is nowhere obvious to take it. Recovered wash water is a liquid, and a household waste centre will not accept liquids by the drum. Even sealed, unopened stock cannot go back to a supplier, because once it has left the site it cannot lawfully be resold. We are still establishing what the correct route actually is, and we would rather say that than pretend.

Protecting a garden is mostly done before the first drop of chemical is mixed. Every border, shrub and run of lawn gets soaked with clean water first, because a plant already full of water takes up very little of anything else, and because dilution at the leaf is worth more than caution at the sprayer. It reduces the risk substantially. It does not make it zero, which is why the planting gets rinsed again at the end and why some things get covered rather than trusted.

The post-treatment deserves stating plainly rather than slipping past. Leaving a light diluted pass on the clean surface to dry does extend how long it stays bright, because it deals with the spores that are already settling before you have packed the van. It is also a residue on a surface that children sit on and dogs walk across. So it is offered, explained, and given a re-entry interval — never applied quietly because it makes the result last longer and nobody asked.

There are three patios and drives in this collection now. On one we withheld the chemistry because the day was too hot and it would have bleached the blocks. On another the customer did not want it and got a plain water clean. On this one it was the right call and it was used properly. That is the actual point: it is a decision, made in front of the specific surface on the specific day, and a contractor who does the same thing everywhere is not making it.

One last note, on why you will read close to the opposite of much of this if you go looking. Ask the question today and you are handed a generated summary that reads like an answer from the search engine itself, assembled from whatever happens to rank — and what ranks is contractors reassuring each other on social posts and supplier blogs. It will tell you the chemistry breaks down into nothing but salt and water with no footprint. It largely does break down, and chloride really is a major end product; but where it meets organic matter it also forms chlorinated compounds the environmental literature records as persistent and toxic to fish. A comfortable half-truth, repeated often enough to be summarised back to you as fact. We would rather give you the version you can check.