COST Action 682 entitled "Integrated Wastewater Management" was active from 1992 and will expire in February 1998. A new Action entitled "Optimal Management of Wastewater Systems" is proposed. This new Action covers all aspects of wastewater management systems (i.e. collection, treatment and disposal) with regard to optimizing the performance of the complete system and also focuses on the development of new sustainable wastewater management strategies.