“The jungle programme”, as we call it, is back. “I’m a celebrity get me out of here”, to give it its proper name, is into the final week of its current series on ITV. As a family we have been paying more attention to it than in recent years, partly because many of this year’s participants are more familiar to us than those who took part in the last few series, and partly because the interaction between the presenters (Holly Willoughby and Dec Donnelly) has been so entertaining. Ant & Dec were always very watchable and so are Holly & Dec.

This time round it seems like lots of the action centres around the dunny, which this definition from the Oxford Dictionaries website tells us is “NZ Australian informal A toilet”. Its origin is given as “Early 19th century (in the sense ‘dung’): from dialect dunnekin ‘privy’, probably from dung + archaic slang ken ‘house’.” Having never been to Australia or New Zealand I don’t know if all lavatories are described as “dunnies”. The word seems to imply an outdoor convenience, the kind of place where dangerous spiders lurk. That’s certainly the case in “I’m a celebrity get me out of here”. It’s contained in a hut away from where the contestants sleep, eat and hang out. The jungle-dwellers have been shown discussing it and emptying it. A quick web search reveals plenty of clips and stories from previous years on the same subject, none of which I feel compelled to investigate further right now, not even the one titled “Toff gets covered in ‘dunny juice’”. (Georgia “Toff” Toffolo was crowned Queen of the Jungle last year.)

Watching two of this year’s participants struggling to empty the dunny I reflected, as I have done often over the last 10 years, on more sensible ways to deal with human waste. The rest of this piece shares what I have learnt in the last decade. The information would have saved a lot of lives throughout human history if our ancestors had known it and acted on it.

The simple rule, when dealing with human waste, is to keep the yellow stuff and the brown stuff apart. Separately they can be dealt with much more easily than when they are combined. They are kept separate when they are inside your body and this should apply when they leave your body. This should be general knowledge but as a species we have ignored it and, throughout history, mixed everything together. The result stinks, it spreads disease, and it poisons water supplies. With our indoor plumbing, and everything flushed away to be processed as far away as possible, we 21st Century Londoners, like most city dwellers, don’t need to think about it. Our ancestors, however, paid the price for not knowing the most important rule of waste processing. Their drinking water became polluted and people died before their time.

This lesson was brought home to me about 10 years ago, chatting to a friend (a music manager) after a gig. He and his wife are involved with a charity that builds wells in remote African villages. As well as the technical business of digging the wells to provide clean drinking water for people who had previously walked for miles to find it, the charity educates the villagers on how to keep the water supply safe for years ahead.  They give the advice given in the opening sentence of the paragraph before this one: keep the yellow stuff and the brown stuff apart. If the participants in the jungle programme did this, their “dunny duties” would be very different. They wouldn’t have to empty heavy vats full of foul-smelling, unhealthy liquid. The components would be much more manageable, and could break down in the soil much more easily, if kept apart.

For you and for me the fundamental rule about managing human waste might not have much practical use right now. But you might end up in a place without reliable indoor plumbing, an African village perhaps, or a jungle location full of famous people, or post-Brexit Britain. And if you do (and I know that this is the third time I’ve told you this) keep the yellow stuff and the brown stuff apart.