Toilets--the facts.

FAECAL PERILS

Every day, every person on earth emits from their body around 100 grammes of faeces and 1.5 litres of pee. From the emitter's point of view these are 'wastes' which need to be privately, congenially and safely disposed of, although they contain nutrients useful for fertilizer--if you can bear to capture them. From the public health point of view, the risk is from the pathogens in the shit: urine is virtually sterile.

One gram of faeces can contain:

10,000,000  viruses
 1,000,000  bacteria
     1,000  parasitic cysts
       100  parasitic eggs (1)

Millions of these viruses and bacteria live in our digestive tracts and help make them tick, or are produced by symptomless infections forming part of our natural defences. But the rest of the toxic load represents a threat that, given shit's daily proximity, make it more dangerous to human health than any other substance.

THE F-DIAGRAM (2)

The F-diagram, designed 50 years ago, has not been bettered as a way of showing the routes taken by faecal pathogens when they end up in people's mouths and cause disease. Diseases euphemistically known as 'water-related' are really 'shit-related'--though water is important if hygiene is to keep them at bay.

LEAVING SHIT LYING ABOUT

People who don't have toilets and pipes to flush away their excreta or confine them in pits, practise what is called 'open defecation'--meaning that they 'go' behind a bush or on the banks of a stream, and leave their detritus to biological rendition. In places with few inhabitants, hot sunshine, scavenger dogs or pigs and rigid toiletary codes, maybe that used to be okay. Maybe in some places it is still healthier (and certainly more congenial) than a foul latrine. But in a crowded world, 'open defecation' is a no-no. In toilet coverage, Africa is weakest by far, but there are many more open defecators in Asia.

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THE DIARRHOEAL KILLING FIELDS

Around two million deaths a year are associated with diseases of dirt and squalor. Most are due to diarrhoeal diseases, but there are many others. The vast majority of these deaths are in children under five, almost all in developing countries, and almost all among poorer families.

URBAN TOILET CRISIS

Provision of decent toilets--nice to use, confine shit safely, don't smell horrible, don't attract insects--lags dreadfully in rural areas compared to towns. WHO and UNICEF (guardians of sanitary statistics) state that 611 million people in urban areas lack toilets, compared to 2,001 million in rural areas.(6) But cramped conditions in slums and shanty-towns--many of which are not included in these statistics because they and the people in them are regarded as 'illegal'--mean that urban sanitation needs are far more acute.

Urban dwellers lacking adequate provision of sanitation, by region (7)

Africa                   50-60%
Asia                     45-60%
Latin/America/Caribbean  25-40%

NUTRIENTS FROM HUMAN WASTES

Most people think that the shit is the excreta with the fertilizing potential. But actually, almost all the nutrients are in the pee. Faeces have to be closed off and composted for 12 months to be sure that all pathogens have died, whereas urine is safe to use in dilute form immediately.

THE SANITATION 'LADDER' (8)

Safe sanitation can be as basic as using a spade. If a special facility is built for the home, it can range from an outdoor protected pit surrounded by a brush fence, to a streamlined indoor bathroom with flush toilet and sewerage connection. Since the latter-mandatory for homes in most industrialized countries--costs between $400 and $1,500, it is impossibly expensive in poor environments, as well as profligate with water. In sanitation programmes today, a 'ladder' of less costly alternatives is often presented, with the idea that improved status and wealth will permit the toilet consumer to aspire to higher rungs.

SIMPLIFIED SEWERAGE

Small-bore pipes laid in lanes can be connected to hand- or handle-flushed toilets. Output can be connected to main sewer or led to wetland. Needs strong community involvement for construction and maintenance, and only possible where housing is permanent and tenure assured. Cost: $40-300

THE COMPOSTING UD TOILET

The urine-diverting toilet is the aristocrat of ecological sanitation, with separate compartments for the excretory functions. Dilute urine can be used directly as fertilizer; alternating shit compartments, flushed with ash or soil, take little space because volume is dramatically reduced. Non-polluting. Cost: $90-350

THE POUR-FLUSH TOILET

Has a water-seal pan, like a regular WC, and is flushed by pouring water by hand. Much preferred to 'dry' pits by those who traditionally use water for cleansing, and by many others for olfactory advantages. Cost: $40-260

THE 'VENTILATED IMPROVED PIT' OR VIP TOILET

A ventilation pipe inserted into the pit and rising high above the toilet house significantly reduces smells and insects. No water needed; can use two alternating pits and recycle composted material. Cost: $40-260

THE COVERED PIT, WITH SQUAT SLAB AND KEY-HOLE LID

Prevents contact between excreta and humans, animals and insects, and has a shelter for privacy. But can smell, and needs emptying or replacing when full. Cost: $10-50

THE SMALL SPADE

No construction costs. Enables the 'open defecator' to sanitise his or her tracks. No use in towns or concentrated rural settlements.

(1) IRC, Delft, 2007. (2) EG Wagner and JN Lanoix, WHO, Geneva, 1958. (3) State of the World's Toilets, WaterAid, 2007, based on data from WHO/UNICEF Joint Monitoring Programme. (4) Ibid. (5) WHO, World Health Statistics, 2007. (6) 2004 figures, www.wssinfo.org (7) David Satterthwaite and Gordon McGranahan, State of the World 2007: Our Urban Future, Worldwatch Institute, Washington DC, 2007. (8) Source for costs: David Sattherthwaite and Gordon McGranahan, UNHDR, 2006. (9) R Otterpohl, in Water, vol 21, 2001.

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