A study by the National Environmental Engineering Research Institute (NEERI) has found that faecal contamination levels are ‘too numerous to count’ (TNC) in water samples collected from select locations of the Thevara-Perandoor (TP) and Edappally canals in Ernakulam.
The agency was entrusted by the Kerala State Pollution Control Board to conduct a feasibility study on developing a process package for the treatment of domestic sewage discharged into the Edappally and Thevara-Perandoor canals in Ernakulam and Patolithot and Valiyat canals in Kollam. The study was initiated after the National Green Tribunal directed the government to take steps to check the indiscriminate degradation of canals caused by illegal discharge of untreated wastewater into them.
The draft final report on the feasibility study found that faecal coliform was detected as TNC at four out of the eight sample locations in the Thevara-Perandoor canal. In two locations, the levels were recorded in the range of 2,510 CFU (colony-forming units)/100 ml to 3,000 CFU/100 ml. Faecal coliform was detected as TNC in one of the six sampling locations of the Edappally canal. In the other four locations, the levels varied from 201 CFU/100 ml to 20,022 CFU/100 ml.
The faecal coliform levels in the Patolithot canal ranged between 85 CFU/100 ml to 3,500 CFU/100 ml. In Valiyat canal, the levels varied between 50 CFU/100 ml to 9,450 CFU/100 ml. The NEERI had conducted the feasibility study in April 2024 and February and October this year.
The report said that the water quality of Edappally, Thevara-Perandoor, Patolithot and Valiyat canals had been threatened or impaired due to discharges of stormwater and domestic sewage from the catchment area. There is no existing or inadequate sewage treatment facility along the entire stretch of the canals. The canals have turned into collectors of pollutants that emanate from various drain discharges, it said.
The agency recommended that the pollution loads discharged into the canals needed to be adequately treated in the well-designed proposed sewage treatment plants before being discharged into inland surface water.
Published – November 28, 2025 08:22 pm IST
