A set of indicators for the assessment of temporal variations in the sustainability of sanitary systems

The sustainability of an urban water system was studied by application of a set of indicators that focuses on environmental issues and the efficiency and performance of the technical system. Temporal variations of indicators reflecting freshwater resources, drinking water, wastewater and by-products , were investigated for the water and wastewater system in Goteborg. Extend ed time series of precise data were available for quantitative indicators s uch as water consumption, energy use and discharge loadings. Qualitative in dicators such as drinking water quality, sewage sludge quality and ecosyste m status were more difficult to assess, a situation complicated by variatio ns in criteria set in different countries. Although large urban water syste ms are often considered unsustainable, the set of indicators demonstrate th at the water and wastewater system in Goteborg has moved towards a more sus tainable status; recycling of nutrients to agriculture remains, though, a m ajor concern. (C) 1999 IAWQ Published by Elsevier Science Ltd. All rights r eserved.