Approach to assess and control inflows into sewers

Abstract

Performance of urban water systems is severely affected by a significant proportion of the total flow originating from inflows either illicit, excessive or having a detrimental effect in the water cycle. Affected subsystems include separate (sanitary or storm) and combined sewer systems as well as other components of the water cycle, including wastewater treatment and receiving waters. Despite recognised as an important source of systems’ performance deterioration, the actual dimension of the problem is often unknown and a structured process to reduce these inflows is not internalized in the water utilities. A comprehensive methodology is presented as well as a validating process involving a number of Portuguese water utilities willing to tackle this issue. An overview of the main opportunities and challenges identified for methodology implementation are also summarised. The proposed methodology allows insight for sound improvements in the performance and efficiency of urban water systems as a whole, contributing to increase knowledge of the existing situation and to support action plans, ranging from short to long term in continuous improvement process.