Background Combined Urban Drainage Networks (UDNs) collect and convey both wastewater and storm water. This mixed water is sent to wastewater treatment plants (WWTPs) before being released to the environment. During heavy-rain events, UDN and WWTP capacities can be easily exceeded, causing untreated water discharges, known as combined sewer overflows (CSOs). To avoid this, modern UDNs include infrastructure such as tanks, gates and pumps, which can provide storage during heavy rain and release water gradually to the WWTP. Real-time control (RTC) based on model predictive control (MPC) has been shown to be efficient for the management of UDNs. However, RTC is based on managing flows and does not take into account the polluting load (quality) of the water, which varies considerably depending on the rain events and storage periods. Similarly, the efficiency of WWTP processes depends on both the quantity and quality of the treated water. Untreated water may be refused at different by-pass points, leading to CSOs. Until now, UDNs and WWTPs have been managed separately. It is clear that integrated and coordinated management of quantity and quality in both systems is required in order to optimise overall efficiency and maintain the quality of waters into which treated water is discharged, as required by the EU Water Framework Directive (2000/60/EC). Objectives The LIFE EFFIDRAIN project will demonstrate an integrated real-time control (RTC) strategy for UDNs and WWTPs to minimise the discharge of pollutants into receiving waters. The strategy will be tested in Bordeaux (France) and Badalona (Spain) and will: Demonstrate integrated RTC management of the waste water systems at the pilot sites during a range of rain events; Assess and quantify the benefits of the proposed solution compared to the control strategies currently in use; and Validate the applicability of the proposed solution in a variety of urban areas. LIFE EFFIDRAIN will install sensors at the pilot sites to generate data that will be used to create a database of environmental scenarios taking into account weather conditions, real control actions and their effects on the different subsystems. It will also provide operational quality forecasts for both pilot sites, covering total suspended solids in sewer systems. Once the capability to monitor and forecast quality parameters in the sewer system and the WWTP is in place, procedures to compute optimal control strategies for water quantity and quality will be developed. Expected results: LIFE EFFIDRAIN will result in: 1. A new approach to real-time joint management of UDNs and WWTPs in order to protect receiving waters. This approach will be applicable in a wide variety of wastewater systems. The project will demonstrate at least a 40% reduction in the total yearly polluting load of receiving waters caused by CSOs; 2. The implementation of the procedures at the Mediterranean pilot site in Badalona (Spain) and the Atlantic pilot site in Bordeaux (France); 3. A cost-benefit analysis of the LIFE EFFIDRAIN approach taking into account socio-economic and environmental aspects; 4. Guidelines for transferability and replication; and 5. Guidelines to help the development of relevant EU environmental regulations.