The tanks will ensure a minimum chlorine level of 0.2 ppm, especially in tail-end streets

Over the past one week, Chennai Metrowater has installed chlorination tanks across the city to ensure that the residual chlorine level is maintained in the piped water supply.

According to sources in the Metrowater, around 100 spot chlorination tanks have been installed in the tail-end areas across Chennai, including newly merged areas. Chlorine levels that are as high as five parts per million (ppm) at water distribution stations become negligible by the time drinking water reaches consumers, particularly those in the dead-end streets.

The installation of such tanks with a capacity of 250 litres is an attempt to maintain the chlorine level at a minimum of 0.2 ppm in the piped water supply. Sodium hypochlorite solution would be mixed into the water and the tank will be connected to the pipeline nearby. This measure would ensure that the water supplied through pipeline has adequate chlorination throughout the day, said sources.

This step is in the wake of the recent cholera outbreak in the city.

The areas where chlorination tanks have been installed include Tiruvottiyur, Vyasarpadi, Pulianthope and Perungudi. Metrowater officials said problems of insufficient chlorine level arise when water is drawn during non-supply hours too.

Residents in areas such as Broadway, Sowcarpet and Anna Nagar West often complain that the drinking water is not adequately chlorinated. M.Subadra, a resident of Broadway, said that old pipelines in some streets must be replaced besides ensuring presence of chlorine.

In some parts of Mogappair and Anna Nagar West Extension, the chlorine levels in the water are not that high as it is directly supplied from the treatment plant in Red Hills instead of distribution stations.

Nearly 15 chlorination tanks have been put up in Mogappair and Anna Nagar Western Extension.

The zone has many tail-end streets as Ambattur the neighbouring area is yet to be covered with water supply network.

The water agency is also in the process of distributing pamphlets on the supply timing in every zone to discourage use of hand pumps during non-supply hours.