Except in schoolboy jokes, the subject of human waste is rarely aired. We talk aboutwater-related diseases when most are sanitation-related - in short, we don't mention the shit. A century and a half ago, a long, hot summer reduced the Thames flowing past the UK Houses of Parliament to aGreat Stink thereby inducing MPs to legislate sanitary reform. Today, another sanitary reformation is needed, one that manages to spread cheaper and simpler systems...