Rampant extraction: ground water level drops drastically

Summer has not officially set in but the fears of an imminent water crisis has. Concerned about facing shortage of water due to the failure of northeast monsoon – which followed a rather poor southwest monsoon at a majority of the districts – more and more residents are turning to digging new borewell.

Alarmingly, though the increasing number of borewells are leading to over- exploitation of groundwater leading to the fast depletion of the water table, neither the Chennai Metropolitan Water Supply and Sewerage Board (Metrowater) nor any other government agency have any mechanism to check the indiscriminate tapping of this increasingly scarce resource.

The private companies that are engaged in borewell digging say they have been getting more contracts this year due to the failure of northeast monsoon. “Although it is common to get more contracts during the summer, we are witnessing more orders this year,” said S Periyasamy, proprietor of Vetrivel Borewells.

According to Periyasamy, the ground water level in the city has gone down compared to last year. “In Kolathur, we drill up to 70 to 80 feet to get water. In areas like Nungambakkam, the water level went down beyond 80 feet. At Choolaimedu, however, water is available only at a depth of 450 to 500 feet. Overall, the water level in many parts of the city has gone down by 30 feet when compared to last year,” he said.

A staffer from another firm, Murugan Borewells, who were engaged in drilling on a street in Choolaimedu said that his company has also been receiving more contracts this year. When asked whether the owner of the building or the drilling firms need to get permission to dig the wells, he said it was not necessary to dig a borewell inside one’s own premise.

This absence of regulation has led to the present scenario where the Metrowater and Chennai Corporation officials have no data on the number of wells in the city, nor any mandate to monitor them if they are dug in private property. “However, we will take action when the borewells are dug up on the roads or pavements. Only, the government has the right to dig borewells in public places,” a Chennai Corporation official said.

Much of the business that the borewell drilling firms are getting this summer are from the residents who are commissioning additional well in their premises. “I have two borewells, but there are about 10 tenant families in the building. I will not be able to provide water to all of them if the Metrowater cuts supply in the peak summer. So I have commissioned another borewell,” said a resident of Choolaimedu seeking anonymity.

When asked about the indiscriminate exploitation of groundwater, he said that he was forced to dig the new borewell due to the government’s failure to provide water. “Government should either supply water adequate quantity of water, or allow us to dig borewells,” the resident added.

“According to rules, there should be at least 100 metres between two wells and residents should get permission from concerned authority if they use motors with capacity higher than 0.5 HP. The government should encourage rainwater harvesting at least,” said Sekhar Raghavan, director, Rain Centre, an organisation that has been working in the field of water conservation for several years.

In a welcome development, the Tamil Nadu Combined Development and Building Rules, 2019, has incorporated conditions including ones that insist on recharge wells instead of recharge pits and harvesting rainwater from rooftops and driveway runoff. These can have a positive impact on the groundwater situation in the city.

The Greater Chennai Corporation has issued notice to one of the biggest textile shops in T Nagar for allegedly digging a borewell on the pavement. “We have received complaints from residents alleging that the textile shop was digging the borewell on the pavement. Immediately we visited the spot and issued a notice,” the official said. The shop management claimed they were digging the well on their land. “But, the spot is very close to the pavement,” the official added. They have asked the private establishment to give a written undertaking, said the official, adding that action would be taken against them if it was found that the spot where the well was dug was a public land.

In Tamil Nadu, the following per capita norms are adopted for water supply to towns.

Corporations 110

Municipalities 90

Town Panchayats 70

As per 2011 census, Chennai had a population of more than 70 lakhs. If the Metrowater supplies 110 litres per person per day, it ought to supply 770 MLD every day

As per the data collated by the State Ground and Surface Water Resources Data Centre for January has shown that groundwater table has gone down at 18 districts in Tamil Nadu. Chennai is the worst affected, with all its taluks being categorised as overexploited. The taluks are classified under categories based on the assessment by the Data Centre – overexploited, critical, semi-critical and safe blocks. The overexploited and critical blocks are notified as A category blocks (where the groundwater extraction is 90 per cent or more), while the semi critical and safe blocks come under B category blocks where the extraction is below 89 per cent. The government has prohibited new schemes in the overexploited and critical blocks, restricting the schemes only to category B blocks. Chennai is among the worst affected – all 20 firkas in the five taluks in Chennai region – Egmore-Nungambakkam, Fort Tondairpet, Mambalam-Guindy, Mylapore-Tiruvallikeni and Purasawalkam-Perambur – are overexploited, with groundwater extraction exceeded 100 per cent.