Coimbatore Corporation officially broke ground on a five‑million‑litre‑per‑day (MLD) sewage treatment plant (STP) near Chinnavedampatti lake on Wednesday, July 8, 2026. The move comes after the Madras High Court dismissed a writ petition that sought to halt the project, clearing the legal path for the municipality’s underground sewerage scheme.

Legal Background and Court Ruling

The dispute originated from Government Order (G.O.) 4D No. 50 dated May 30, 2025, which authorized a ₹318.9 crore underground sewer network covering Chinnavedampatti, Saravanampatti and Vellakinar. Environmental activist V.S. Kailasamy filed a writ challenging the order, arguing that the STP would jeopardise the lake’s ecosystem and that both treated and untreated effluent could be discharged nearby.

High Court’s Decision

During the hearing, the Division Bench—Chief Justice Sushrut Arvind Dharmadhikari and Justice G. Arul Murugan—recorded the Additional Advocate‑General’s statement that the Tamil Nadu Pollution Control Board (TNPCB) had already granted consent on May 6, 2026. The petitioner’s counsel then requested permission to withdraw the writ and approach the National Green Tribunal (NGT) for any further relief. The Court, in its order dated June 29, 2026, allowed the withdrawal and dismissed the case, effectively green‑lighting the project.

Technical Features and Environmental Safeguards

The STP will employ Sequencing Batch Reactor (SBR) technology, a proven method for high‑efficiency biological treatment. Treated effluent will be disinfected in line with NGT standards, and its quality will be continuously tracked through an Online Continuous Effluent Monitoring System (OCEMS). OCEMS feeds real‑time data to both the TNPCB and the Central Pollution Control Board (CPCB), ensuring transparency and rapid response to any deviations.

Revised Discharge Strategy

Initially, the corporation planned to release the treated water directly into Chinnavedampatti lake. However, after extensive environmental review, the plan was altered: approximately five MLD of treated water will now be discharged into the lake’s outlet canal, allowing it to flow downstream to Sulur lake. This adjustment mitigates the risk of lake eutrophication while still providing a sustainable water reuse pathway.

Project Timeline

Officials assure that the STP construction will be completed within a year, marking a significant step toward improving Coimbatore’s wastewater management and meeting national water‑quality targets.