For those of us who think the only decent toilet is one that flushes our wastes out of sight and out of mind, sewers seem essential – and in many countries, flushing with water is mandatory. But in the 19th century there were many advocates of ‘dry conservancy’ – composting toilets that recycled muck. In today’s water-conscious world, these have made a comeback. Ecological enthusiasts argue that providing thousands of litres of water treated to drinkable quality to every toilet user, only to have it soiled, discarded, and expensively retreated, is stupendously profligate with a precious natural resource. To provide that volume of water, under pressure, is not possible in many poor and water-stressed environments. Among donors, the pendulum has therefore swung in favour of the ‘on-site’ solution, with sustainability the watchword of today’s sanitation assistance programmes. Some even refuse to fund sewer-based sanitation. But are sewers unfairly excoriated? We asked David Satterthwaite to make the case for sewers. And to give pits their due, we invited Mayling Simpson-Hébert to offer a brief riposte.
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