Around 242.73 MLD of raw sewage enters storm water drains, mixes with waterbodies Share Via Email | A+A A- By Express News Service CHENNAI: Only around half of the sewage generated in Chennai Metropolitan Area (CMA) is collected by the existing sewerage system, leaving the remaining uncollected, the CAG report tabled in Assembly on Thursday said. As of March 2019, only 52% of the sewage in the CMA was being collected through the sewerage system. Of the collected sewage, only 88% was being treated before being let out, the report stated. The audit stated that the Government of Tamil Nadu, in response to the audit, said that the claim that only 52% of sewage was collected was based on theoretical calculations. However, the CAG stated that the reply was ‘untenable’.