Chennai Metro Water Prepares for Monsoon, Tackles Sewer Blockages

The Chennai Metropolitan Water Supply and Sewerage Board (CMWSSB), popularly known as Metro Water, has begun precautionary measures ahead of the monsoon. However, waste such as clothes, diapers and sanitary napkins dumped into sewer lines continues to pose a major challenge, causing blockages and sewer overflows.

Sewer Desilting Work Underway

Metro Water has desilted around 6,000 km of active sewer lines twice, covering approximately 1.7 lakh manholes. The third phase of desilting work is currently underway and will continue throughout the monsoon season, according to a senior official.

Of the city`s pumping stations, 423 are equipped with automated Internet of Things (IoT) systems. These stations switch on when water reaches a preset level and switch off when the level falls, even when workers are not present.

Waste Disposal Causes Sewer Blockages

Officials said sewer blockages are not confined to any particular neighbourhood. Clothes, sanitary napkins, diapers and other waste are reportedly dumped into sewer systems in slum areas, high-rise apartments and Tamil Nadu Housing Board flats, leading to blockages and overflows.

Water Quality Testing to Increase During Rains

To help prevent waterborne diseases, Metro Water plans to increase water sample testing to 1,800 samples during the rainy season, compared with 600 samples on normal days. Additional samples will be collected from Tamil Nadu Urban Habitat Development Board residential complexes.

Measures to Handle Heavy Rainfall

Officials said the city`s infrastructure managed by the Greater Chennai Corporation can handle up to 20 cm of rainfall a day. However, rainfall intensity remains unpredictable, as seen during the floods of 2021 and 2023.

As part of its preparations, Metro Water has raised the height of 20 pumping stations in low-lying areas and installed generators at these locations. Additional generators, diesel supplies for one to two months and sandbags have also been kept ready.

A total of 740 machines, including high-speed sewage suction vehicles, are being prepared for monsoon operations. Metro Water owns 600 machines, while 173 are expected to be outsourced under the Annal Ambedkar Business Champion Scheme. Around 130 suction lorries will also be brought in from other districts and shared with the Greater Chennai Corporation.

Rainwater Harvesting Systems Need Maintenance

Rainwater harvesting structures in approximately 10 lakh of Chennai`s 12 lakh buildings are reported to be functional, while the remaining two lakh require maintenance.

Officials said around 90% of rainwater harvesting structures in large houses, h high-rise buildings, hospitals and IT companies are functional. However, maintenance remains a concern in smaller houses.