Chennai Metrowater plans to study the acute diarrhoeal disease (ADD) cases reported to the Communicable Diseases Hospital, Tondiarpet, in the last four years as part of its measures to improve the sewer system.

Officials of the water agency said that the data, to be obtained from Chennai Corporation, would help it identify the areas from where more cases were reported and the outbreak of ADD was frequent. Wherever water contamination was established as the cause for the outbreak, Metrowater would step up monitoring of the sewer system.

The study would be completed in a fortnight, an official said.

Besides slum areas across the city, the water agency would concentrate on localities in its Area I (Kodungaiyur and Tondiarpet), Area III (Perambur and Vyasarpadi), Area IV (Kilpauk and Ayanavaram) and Area VI (Triplicane and Chepauk) where the complaints recur.

The desilting equipment would be operated twice a day to clean the sewer lines across the city and to prevent blocks during monsoon. Now, the equipment is used once a day either in the morning or evening.

At present, there are nearly 77,000 manholes in the city.

Additional manholes would be provided in places where the distance between two manholes is found to be more than 50 metres.

Nearly 300 manholes are expected to be added to facilitate better maintenance of the sewer network, the officials said.

Steps are being taken to commission the sewage pumping stations where strengthening work is under way, including one on Greams Road, the officials added.