“I can’t think of any other aspect of my life where I come into such close proximity to mould and algae…”

As the opening line in a book it wouldn’t exactly be an attention grabber, but as a harsh fact of caravanning life, it’s a reality. And it’s one that I have to deal with on an annual basis.

I’m sure that I can remember putting a shiny white caravan into its storage area at the end of each season – and yet each spring it sits there, looking as though it’s just emerged from a particularly filthy swamp. It’s a thousand shades of light and dark green, and home to more single-cell plant and animal life than a David Attenborough special.

Has my caravan developed a secret ability to take itself off to wild and exotic locations during its winter break, perhaps resulting in a collection of Herbie-like adventures of its own? A few nights in the forest here, another couple in the local pond there, and a few more in the grubbiest areas of a working farm for good measure.

However it happens, each spring I’m faced with the same dilemma: how to turn it back from primeval to pristine. A bucket of soap and water simply wasn’t cutting the mustard, so this year I invested in a power washer (with optional ‘Gyroturb spinning, rotating heads’, no less).

I excitedly unpacked it from the box and assembled the parts. I filled the additives dispenser with a proprietary fungal wash called ‘Gleamo Clean’, ‘Magic Sparkle’, ‘Algae Zap’ or something similar. I connected the water hose and eagerly turned on the power…

A few moments of whirring and slooping later, and a high-velocity stream of bright-orange foam launched itself from the end of my power-wash lance. It was like a scene from Ghostbusters. Within seconds, not only was the caravan covered in a thick layer of expanding bubbles, so was I, the children’s pets’ hutches, and most of the garden. And in the rapidly multiplying mountain of foam, the on/off switch for the power washer proved remarkably elusive. It was only my muffled screams that brought my wife to my aid – thankfully via the power-socket switch.

I’m not sure that the herbaceous border will ever be the same again, and the guinea pigs are now a very unusual colour. The only advantage is that I’m convinced my recurring athlete’s foot is now banished forever.

Eventually, I managed to rinse all of the foam off the caravan and there, finally revealed in all of its glory, was the gleaming white home-from-home that I know and love. Apart from the windows, which seemed to have become frosted for some reason.

I’m sure that I read the instructions properly. But maybe watching some expert cleaning advice from Practical Caravan would help, too.

Visit Martin’s website for information about him, his books and his property training weekends, and follow his adventures on Twitter