Over 2 million tonnes of human excrement is produced daily in cities around the world; less than 2% is treated and the rest discharged into watercourses or into the soil.
Problems of microbial quality and occasional outbreaks of waterborne diseases have been reported across the European region, even from countries with high standards of supply. Systems for detecting waterborne disease are generally poor, and in practice only the larger outbreaks have been detected. Microbial pollution is especially prevalent in small supply systems and those with intermittent service. Private supplies may not have been subject to such stringent standards as public supplies.