With the construction of residential complexes in the merged areas proceeding at a frantic pace, the decades-old conduit pipelines, the backbone of the city’s drinking water distribution, are under threat.

The land through which these underground pipelines pass is being encroached upon in various areas. The 10-km long-pipelines run from Red Hills reservoir to Kilpauk water treatment plant on New Avadi Road.

Of this, Metrowater sites between Red Hills and Rajamangalam are in danger of being encroached upon. Metrowater lands under which the second half of the pipelines run — between Villivakkam and New Avadi Road — are already heavily encroached. Such activities not only risk damaging the pipeline but also delay any repair as the encroachments have to be removed first.

The three pipelines, laid at various points of time by Chennai Metrowater, are some of the first bits of infrastructure that supplied safe drinking water to the city. The earliest pipeline, which is still in use, was constructed with brick masonry in 1914. With one of the pipelines having collapsed a few years ago, the two remaining ones carry about 250 million litres a day (mld).

These lines pass through different areas, including Surapet, Puthagaram, Rajamangalam and New Avadi Road, before culminating in Kilpauk water works. Several properties adjoining the Metrowater’s lands in these areas are being readied for construction.

Recently, elected representatives in Ambattur objected to a construction firm carrying out digging activity on a stretch near Metrowater’s site, a move that risked damage to the pipeline. The water agency has asked the firm to stop construction of the culvert to save the line from any damage.

Moreover, some stretches are used as short cuts by residents and heavy vehicles. Some residential colonies for instance have laid roads on stretch over the conduit lines to gain access to Water Canal Road that connects with Inner Ring Road.

Metrowater has taken to painting inspection chambers, which resemble tanks, on their plots of land to indicate the presence of pipelines. It has also put up boards to indicate that the land belonged to the water agency.

Residents of Puthagaram and Surapet also suggested that the agency could close the new lanes that were created illegally.

In other cases, said B. Kingsly, a resident of Surapet, Metrowater should provide culverts to enable vehicles to cross the stretch beneath which the pipelines are laid.

Sources said there is an urgent need to fence strips of land belonging to Metrowater to secure the conduit lines. Most of these strips of land are at least 15 metres wide. A separate wing was essential to safeguard such infrastructure from further encroachments, said officials.

Meanwhile, the water agency has called for tenders to reconstruct the two pipelines into one concrete box channel with carrying capacity of up to 400 mld.

Sources in Metrowater said that the work would initially be taken up in a stretch of five km between Red Hills reservoir and Rajamangalam as the other stretch has been heavily encroached upon.

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