In the industrialized world, most of us (except those who have septic tanks) rely on wastewater-treatment plants to remove our excrement from the drinking-water supply, in great volumes. (Toilets can use up to 30 percent of a household’s water supply.) This paradigm is rarely questioned, and I understand why: flush toilets, sewers and wastewater-treatment plants do a fine job of separating us from our potentially toxic waste, and eliminating cholera and other waterborne diseases. Without them, cities wouldn’t work.
But the paradigm is flawed (isn't it always?-Psota). For a start, cleaning sewage guzzles energy. Sewage treatment in Britain uses a quarter of the energy generated by the country’s largest coal-fired power station.
IN the far reaches of Shaanxi Province in northern China, in an apple-producing village named Ganquanfang, I recently visited a house belonging to two cheery primary-school teachers, Zhang Min Shu and his wife, Wu Zhaoxian. Their house wasn’t exceptional — a spacious yard, several rooms — except for the bathroom. There, up a few steps on a tiled platform, sat a toilet unlike any I’d seen. Its pan was divided in two: solid waste went in the back, and the front compartment collected urine. The liquids and solids can, after a decent period of storage and composting, be applied to the fields as pathogen-free, expense-free fertilizer.