Anyone looking for cheap laughs and toilet humour might imagine that Rose George's book examining what happens to human waste across the world would be a good place to start. It's not. The author doesn't think her subject is funny. From the start, she makes it clear that she's sick of bathroom puns and doesn't think that four in ten people in the world having no access to a toilet is a joke.

George passionately believes we should take her subject seriously instead of being embarrassed by it. She laments the lack of academic research into toilet culture. That the brightest brains rarely choose to work in the sanitation industry, and celebrities don't put their names to latrine-building programmes as gamely as they do, say, clean water schemes, is further evidence that we are ignoring a global health crisis.

She aims to steer clear of toilet trivia, but I'm glad that the book contains enough curious details to pep up each chapter. Facts about the world's most expensive toilet (designed for Nasa's space shuttles for $23.4 million) and how to make the best fake turds to test toilet flushing efficiency (the answer lies in soyabean paste) will turn its readers into entertaining, if sometimes tasteless, dinner party guests.

As well as descending into the sewers of New York and London, George's travels take her to biogas units in China that turn human sludge into fuel and communities condemned by India's caste system to work as “manual scavengers” disposing of other people's waste in leaky wicker baskets. She highlights the contrast between sophisticated toilet designs in Japan that play music while they wash and dry your behind - the best of which have a “marriage saving” function that automatically puts down the seat after a man has peed - and “helicopter toilets”, an African practice that involves defecating in a plastic bag and flinging it on to the nearest roof or into an alley, all the time providing stomach-churning details about disease caused by poor sanitation.

It will leave you grateful for our waterborne sewage system in the UK. But it's hard not to wonder - once familiar with the different ways to use human sludge in agriculture - whether we should be doing something more useful with such a plentiful material.

Perhaps most fascinating is the impact that George's research had on her own habits. She washes her hands more; uses less loo paper and always puts the toilet seat lid down when she flushes - to stop a fine spray of urine coating the bathroom. Given that George must now be one of the world's few experts in human waste-disposal methods, it's a shame that these pearls of wisdom, along with her brief analysis of what she has seen, are shunted to the final pages.

The Big Necessity: Adventures in the World of Human Waste by Rose George
Portobello, £12.99 Buy the book

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