A National Environmental Engineering Research Institute (NEERI) study has found the levels of faecal contamination to be “too numerous to count” (TNC) in water samples collected from selected locations of Thevara-Perandoor (TP) and Edappally canals in Ernakulam.
The agency was commissioned by the Kerala State Pollution Control Board to conduct a feasibility study on the development of a process package for the treatment of domestic sewage discharged into Edappally and Thevara-Perandoor canals in Ernakulam and Patolithot and Valiyat canals in Kollam. The study was launched after the National Green Tribunal ordered the government to take steps to check the indiscriminate degradation of canals caused by illegal discharge of untreated sewage into them.
The draft feasibility study final report found that faecal coliform was detected as TNC in four of eight samples in the Thevara-Perandoor canal. At two sites, levels ranged from 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 sites of the Edappally canal. In the other four sites, levels ranged from 201 CFU/100 ml to 20,022 CFU/100 ml.
Faecal coliform levels in the Patolithot channel ranged between 85 CFU/100 ml to 3,500 CFU/100 ml. In the Valiyat canal, levels ranged between 50 CFU/100 ml to 9,450 CFU/100 ml. NEERI conducted the sampling process in April and October 2024 and February 2025.
The report said water quality in Edappally, Thevara-Perandoor, Patolithot and Valiyat canals has been compromised or degraded due to discharge of rainwater and domestic sewage from the basin. There is no existing or inadequate sewage treatment facility along the entire stretch of canals. The canals have turned into collectors of pollutants coming out of various outlets, he said.
The agency recommended that pollution discharged into canals be properly treated in well-designed proposed wastewater treatment plants before discharge to inland surface waters.
Published – 28 Nov 2025 20:22 IST
