We are in the Mingyuan Hotel in Nanning, capital of Guangxi Province in China. This luxury ghetto, with frilly porticoes and tidy flower-beds, is the venue of the first ever international conference on ecological sanitation. Hundreds of delegates have gathered to talk for days about, well, not to beat about the bush, excreta. I have been hired as rapporteur.

My principal problem, I soon discover, is language. Not Chinese. That is all - graphically - translated. I am in the breakfast room enjoying an appetizing banquet of dishes: the Chinese are tremendous foodies, even more concerned about what goes in at the top aperture than what comes out at the bottom. Suddenly I am confronted by Uno Winblad, the Swedish guru of ecosan and the human dynamo behind the conference, for whom it represents the culminating peak of long, difficult and often lonely years of endeavour.

I have committed an unimaginable sin. I have referred in my draft of the conference wrap-up statement to 'human wastes'. Winblad informs me that there is no such thing, and my report won't be worth loo paper. What should I call them then? 'Excreta,' he hisses. In vain do I point out that, for an English speaker, 'excreta' is a more objectionable word than 'wastes'. Anyway, surely excreta only refers to faeces. He becomes apoplectic. Certainly not, urine is also excreted. Other people flee from the breakfast table. Not because of the topic of conversation, you understand. Public-health people talk about these matters as comfortably, even over breakfast, as family planners talk about condoms or nutritionists about breasts. Simply because they don't want to get involved in yet another wrangle about fitting terminology for this most glorious of subjects.

One of the words from the conference is faeco-phobic. This came from a Ugandan. And underlines how common is distaste about - excuse me - human wastes in almost every culture. The Brits, with their propensity for schoolboy humour and scatology, deal with the subject by uproarious laughter. Not the Swedes. Theirs is a more earnest approach. They and the Chinese are the cheerleaders of ecological sanitation. They can discuss 'reduction efficiency of index pathogens in dry sanitation' and 'the practice and strategy of urine diversion in China' without the trace of a smile. And, to be fair, it is a serious subject.

Finding alternatives
About 2.4 billion people - nearly half of all humanity - lack proper means of sanitation. Every year, between two and three million people die of illness caused by poor hygiene, contact with germs, dirty hands, contaminated food, utensils and water. This disease load is usually described as 'water-related'. It is not water-related. It is sanitation-related. Yes, water would allow people to wash their hands and. other bits, and flush much of this noisomeness away. In our own bathrooms and toilets, it does. Where it disappears to we don't much care - we are just delighted to wave it goodbye - because we can afford the sewers, treatment plants and environmental measures to prevent pollution of rivers and seas. Even for us, it is very expensive. It will cost $150-215 billion to achieve full compliance for sewage in the EU by 2010, and in the US, sewage pollution clean-up over the next 10 years is expected to cost $200 billion.

Where people don't even have basic sanitation, these kinds of costs are out of the question. And sewerage requires water for flushing. Many poor countries are water-short. Can it possibly make sense to use 15,000 litres of water per person every year to flush away 35 kilos of shit and 500 litres of pee - the average human output - in a water-stressed environment?

Actually, it doesn't make sense anywhere. What we are doing is adding small amounts of extremely pathogenic material to very large quantities of clean water, and then spending large sums taking the pathogens out of the water again and cleaning up the environment they have contaminated; then sending the water back down the pipes and repeating the stupendously profligate cycle. No-one in their right mind would propose such a sanitation model if we were starting from scratch today, and there is absolutely no possibility of spreading it all over the world. An alternative model - contain the pathogenic material, don't flush it into the landscape - is what ecological sanitation is about.

No, it is not! I can hear Winblad's voice in my ear. Oh yes, those 'human wastes' - I had momentarily forgotten them. They are not wastes but nutrients. Gulp. Does this mean we should eat them? Not exactly, but pretty much. 'Night soil' has been used as fertilizer for more than two thousand years in China and has been vital in agriculture. It still is. A survey in 1993 found that 94 per cent of human excreta were so used. The problem is that if it lies about in the fields untreated, it constitutes a major public health hazard. Well, the shit does, not the urine. The urine is sterile. And it is the urine that contains almost all the nutrients - 80 per cent of the nitrogen, half of the potassium and phosphates. Hence the 'urine-diverting toilet'.

Curious trip
An international conference on ecosan would not be complete without a field trip. So the delegates abandon the Mingyuan Hotel and pile into buses to visit villages in Yongning County. This is the heartland of urine diversion (UD) - and of 'ecological villages' with UD loos in every home, tidy streets, green spaces, biogas plants and other eco-amenities. My bus goes to Tuanyan Puo. Since we are an international group, television cameras accompany us. Please, say our courteous hosts, visit any house you like. One group of agricultural engineers clusters round a plastic cylinder at the base of someone's back wall. A blue tube leads up into what must be the bathroom. They busily debate seals, inflow, outflow, spraying techniques, ammoniac combustion - I had no idea there was so much to discuss about a bottle of pee. The rest of us - microbiologists, sanitarians, environmentalists and a writer - crowd into the tiled bathroom upstairs and peer down the two-ended loo. The tv crew tries to fit in too. Other technical topics spring up: how much ash, lime, or wood chips are added? temperature? moisture content? pH?

This is the most curious tourist outing I have ever been on. I try to imagine a crowd of Chinese visitors fascinated by my toilet. But then, my loo is unexceptional. Soon theirs will be too. There are now 30,000 ecosan toilets in homes in Guangxi province. The urine-diverting toilet, which is clean, nice, compact, cheap to build ($25-36 depending on frills, using locally made plastic pans) and provides an instant fertilizer (urine) and compost for soil building after some months, is truly catching on.

Well, say the sceptics, China is a water-short and faeco-phile society - it's different there. But there are UD toilets on a small scale in Sweden too (they cost rather more) and in Japan, Mexico, South Africa and elsewhere. Public health officials are starting to overcome their reservations. They should. For the case for 'closed-loop thinking' in sanitation - an approach which keeps the polluting material away from the environment until it is composted and safe, and reuses all the organic nutrient components of what we emit from our bodies as a consequence of eating and drinking - is, frankly, water-tight. To provide this as an option for those millions of people who need a toilet, a clean living area, and more to eat, is plain common sense. The squalid environment they currently endure is an outrage against their dignity and health, and an indicator - not an outcome - of their poverty, a point too often ignored.

Sanitation became big news at last September's Johannesburg Summit on the environment. This happened because the US held out for days against agreeing to an international target for cleaning up our excreta-strewn world. They did this as a bargaining chip: they only agreed to the target of reducing by half the number of those without sanitation by 2015 as a trade-off for getting their way on something else. However, they finally accepted that people not only need water, but toilets and cleanliness too. And so resources may begin to flow. The ecosan enthusiasts will be trying to keep at bay the international sewerage firms with their wildly inappropriate water-squandering solutions. And somewhere in Stockholm or China, Mexico or Japan, they will still be arguing about 'human wastes'. Language will always be the biggest problem the sanitarians face.