A metro water study conducted by the state Public Works Department found that 250 million litres of raw sewage enter the city river every day from Kodugaiyur and Perungudi landfills, both the places have functional sewage treatment plants. They also found that most of the STPs are running at lower capacity while the others are working at 50% efficiency due to illegal connections to drains and lack of pipelines in narrow streets. The consumption of contaminated water can lead to gastrointestinal problems, Diarrhea, Nausea, Intestinal or Stomach Cramping, Dehydration, etc. In most cases, long-term exposure to contaminated water can cause cancer, cardiovascular disease, typhoid, etc. 

Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB) stated that they plan to increase sewage treatment capacity by 450 MLD as the plants have a capacity of 745 MLD but are treating 599 MLD currently. Executive director Akash P stated that these gaps will be filled by new interventions and infrastructures including laying new pipelines in unconnected areas. 

Activists have called for more efficient management and officers. Jayaraman Venkatesan, an NGO activist stated that metro water needs to strengthen the sewage wing and bring in separate officials to ensure it gets the same focus. Also, many of the sewage plants and leaking main pipes need maintenance work and repairs. The consumption of contaminated water can lead to gastrointestinal problems, diarrhea, nausea, intestinal or stomach cramping, dehydration, etc. In most cases, long-term exposure to contaminated water can cause cancer, cardiovascular disease, typhoid, etc. In pregnant ladies, it can have a genotoxic and teratogenic effect on the fetus. 

In response, metro water plans to double its tertiary treated water capacity and use it in industrial and commercial functions. They added that the used water will not pollute the lakes but will improve the water storage and groundwater table. 

(Source: https://health.economictimes.indiatimes.com/news/industry/250-million-litres-of-raw-sewage-let-into-chennai-rivers-daily-says-study/91137513 )