As bore wells in Chennai go deeper, water turns hard

File photo of Chennai residents filling water in pots from a Metro water tank on the East Coast road in Thiruvanmiyur.

File photo of Chennai residents filling water in pots from a Metro water tank on the East Coast road in Thiruvanmiyur.   | Photo Credit: N. Sridharan

Over-extraction of groundwater is changing the quality of the water, say experts; call on govt. to desilt and rejuvenate neglected waterbodies

The fact of water being a colourless, odourless and tasteless liquid might soon be a faint memory for most Chennaites as the quality of water in the city plumbs the depths, thanks to the acute scarcity being faced this year.

Chennai is in the midst of its most severe drought yet, and the situation is only going to get worse as global warming contributes to erratic monsoon patterns, says R. Rajkumar, Chief Chemist at Metrowater. “It has been four years since all the surface waterbodies in the State were full. In those days, the lakes at Poondi, Cholavaram, Puzhal and Chembarambakkam were the major water sources for Chennai. The quality of water from these lakes was pure as they are rain-fed. But as the monsoon started to fail, the lakes began to run dry, so alternative sources were resorted to, the most popular being bore wells.”

But now as the water table too steadily declines, wells are being dug far too deep, leading to over-extraction, which is changing the quality of the water. This is because water at deeper levels tends to acquire the properties of the sub-soil layers. “This is why in recent days water has grown increasingly salty. Sometimes, water acquires a metallic taste due to iron contamination. The case is most serious in coastal regions where people violate government rules and dig private wells in close proximity to the sea causing seawater intrusion, which allows highly saline water to enter groundwater channels,” explains Mr. Rajkumar.

Serious consequences

“Medical studies are yet to discover what kind of effect continuous usage of water with high levels of salt content can have on human health,” says Manimegalai, a dermatologist with Government Stanley Hospital. “Many people complain of hair loss due to the hardness of water. The water scarcity itself is causing skin problems as excess sweating creates prickly heat lesions and boils. The scarcity of pure water has also forced people to use RO or can water for drinking purposes although RO water is not great for health because it removes even the natural, essential mineral content of water,” she adds.

As bore wells in Chennai go deeper, water turns hard

D.A. Damodharan, Director, Eco Labs, which conducts water quality assessments, says that higher levels of hardness have been observed in samples of water from areas near the Pallikarnai marshland, Madipakkam and Velachery. “We receive clients who bring samples of water with complaints of not being able to boil it or wash clothes with it,” he says.

“The water we get in our house tastes salty so we can’t use it for drinking or cooking purposes. All of us have bad hair fall because of continuous usage, and there is a lot of salt deposition in the bathroom. We have been using our bore well for around 10 years and over the years there has been a noticeable decline in the water quality as the water has become discoloured and the salt content has increased. This change of water quality concerns me because so much salt in water is not good so we can’t use it for cooking and are forced to buy separate canned water,” says Pavithra D., who lives with her family in Nungambakkam.

Poor implementation

In the early 2000s, when Chennai was facing a similar drought-like situation, late CM Jayalalithaa launched the rainwater harvesting scheme which made it mandatory for all government and residential buildings to include rainwater harvesting structures.

“Rainwater harvesting was a good initiative but due to improper implementation by a majority of the public, failed to contribute to the groundwater table. Most people did not educate themselves on periodic cleaning and maintenance of the media filtration equipment. If the equipment is not cleaned, the rainwater passes through the structure unfiltered. This makes the project ineffective. Moreover due to failure of monsoons the media lies unused and becomes dry. So the structure is sitting useless in most households,” says Mr. Rajkumar.

“Chennai geologically doesn’t have sufficient groundwater. We have never been fully dependent on groundwater like this,” says Elango L. of the geology department in Anna University. “Rather than resort to desalination plants which are costly and ecologically harmful, the government needs to work swiftly to desilt and rejuvenate the city’s many waterbodies which are lying polluted. If this had been done earlier the surface water availability wouldn’t have been so poor now.”

Management key

S. Mohan of the department of civil engineering, IIT Madras, says management of water begins at home. “Large amounts of water are wasted in bathrooms on a daily basis. A single flush of the toilet consumes up to 3 litres of water in most households. On average, one household uses the flush at least 8 times per day. If we take into account the number of households in one apartment complex, it amounts to a lot of water consumption. If recycling and reuse of flush water is made compulsory for all apartments, houses, hospitals and hotels, it will largely reduce water consumption,” he says.

Water storage structures

He also says India should be the next in a line of countries that have underground water storage structures. “During monsoon, Chennai receives a lot of water that flows into the sea. To prevent this run-off we can build a large underground water storage structure. This method is already in use in many countries. California is known to heavily depend on it when it faces drought. Every 4-5 years Chennai faces a water supply drought, and every 4-5 years the city also experiences flooding. If such a project is undertaken it will not only mean stored water but will also prevent flooding by diverting overflow.”

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Printable version | Aug 4, 2020 6:12:59 PM |

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