Prevention of rainwater overflow from combined sewer systems is one of the most important and urgent issues. The amendment in 2003 of the Enforcement Order of the Sewerage Act of Japan stipulates that the improvements must be completed within the specified period (by FY 2013 in principle; however, by FY 2023 if the pertinent areas are extensive) and encourages more efficient and effective sewerage operation. Aiming at the creation of a good social environment, JIWET has been working on the improvement of combined sewer systems via joint research.

Joint research already conducted

「A research on countermeasures against combined sewer overflow (CSO)」、
「Surveillance study on retention facility execution basis plan related toimprovement of combined sewer system works」
「Research on Performance Evaluation of High-Rate Filtering Facility」
etc.

Recent research

「Joint Study on the Improvement of CSO by the Use of Infiltration Facilities」
etc.