In 2003, late Chief Minister J Jayalithaa set a landmark ordinance on Rainwater Harvesting in Tamil Nadu. After the particularly steep drought years of 2001 - 2003, the state government's order mandated that all buildings in Tamil Nadu fix rainwater harvesting structures immediately and store water. It even provided two months for buildings to be fitted with RWH structures, setting an August 31 deadline.
Back then, many believed that the Chief Minister's vision would put an end to Chennai's perennial water woes. Yet, 16 years later, the city once again starves for water, with its reservoirs dipping and its ground water drying up fast. Why? The reasons are plenty, but bad implementation of the Rainwater Harvesting rule ranks among the top, state experts.
"We don't harvest enough rainwater. Had we done it, the gravity of the water shortage we are facing today could have been avoided," Indukanth Ragade, a T Nagar-based urban environmentalist, alleges.
In 2015, Indukanth along with Sekhar Raghavan aka Chennai's Rain Man, who founded the NGO, Rain Centre, in Adyar, conducted a rainwater harvesting survey in the greater Chennai region. Rain Centre did the audit on the government's insistence that a third party undertake it for the sake of autonomy.
However, the NGO's findings badly exposed the state administration, as government buildings were the worst violators of the rainwater harvesting rule, Sekhar states.
"We surveyed 1100 samples which included independent houses, government buildings, apartments and other units. The areas were categorised as sandy (Kottivakkam and Neelankarai) , clayey (Ambattur and Mogappair) and rocky (Tambaram and Chromepet) based on water retention capacity. We found that most police stations, chief and assistant engineer's standalone offices, municipality buildings and town Panchayats got rainwater harvesting methods entirely wrong," he adds.
While broken pipes, clogged pipes, badly maintained bore pits and drains were commonly detected, incorrect rainwater harvesting structures were erected in many plots. Fortunately, some plots also had open wells, which is an effective rainwater drain.
Several buildings used percolation bore pits to direct rain water to the soil. This, according to Rain Centre's study, is ineffective due to the use of narrow pipes. If not maintained well, these pipes and drain clog and any excess water is pushed out, Sekhar says.
Recharge wells, on the other hand, were found to be easier to desilt and took in much more water.
"A person can easily enter the well and clean it. Since it is not a narrow pipe, it can take in much more water and this water will move laterally into an open well (if there is a well in the area), or augment the shallow water table," Sekhar adds.
While the audit did not cover the heart of Chennai, government buildings within the Madras Corporation area also were found to have neglected the RWH ordinance.
The SAF games village located in Anna Sathya Nagar in Koyambedu is a sprawling property with 760 flats, housing IAS and IPS officers and senior government officials. A part of the village comes under the government-rental scheme and others belong to companies including Indian Oil, Reserve Bank of India and SBI. Yet, Rain Centre's investigations four years ago revealed that the complex did not have a functioning rainwater harvesting mechanism.
Corroborating this finding, a resident of SAF games village who lived there for over six months in 2015, said that there was no rainwater harvesting mechanism during her stint in the complex.
"I have moved out from SAF village and I am not sure if they have fixed an operational structure now," she says.
Meanwhile, Chennai Metropolitan Water Supply and Sewerage Board (CWSSB) data suggests that there are over 8.9 lakh rainwater harvesting structures in various buildings across the city. However, the board has not offered relevant data on the maintenance of these structures.
"And how are these numbers of use any way? They are worthless if the efforts do not reflect in the ground water fluctuations in the region," says Sekhar. In 2019, the ground water fluctuations indicate that water table in the city has been dangerously depleting with the average level going down to 7.7 metres.
According to Rain Centre's findings, out of the 88 monitoring wells fixed in Central Madras by the NGO to study the water table, only 10 percent had dried up in 2018. However, this year, only 10 percent of the wells have water in them, says Sekhar.
Deficient rains the cause of dipping ground water?
Chennai receives 1/3 of its water needs from the South West monsoons and 2/3 from North East Monsoons, according to environment experts in the city.
Between 2015 - 2017, the city recorded impressive rains with 2015 witnessing the highest ever recorded rainfall from north east monsoons since 1918. In 2016 and 2017 as well, the city recorded over 100 cms of rainfall during the October - December period.
Much of the blame for the drought situation in Chennai and other parts of Tamil Nadu has been borne by the deficient north east monsoons of 2018. However, Indukanth points out that adding to poor rainwater harvesting, no new reservoirs have been built to store water in a 100 years.
"We have only had 4 reservoirs for the last one century — Poondi, Red Hills, Cholavaram and Chembarambakkam. Most of these reservoirs cannot store to full capacity as desilting has not been done regularly. Even with desilting, storage capacity only increases marginally. Essentially, we are rain rich but water starved," he says.
Echoing Indukant's statements, an official from the Metro Water Board (CMWSSB) confirmed this to TNM.
"Desilting is crucial for any water body as after every rainy season, upto 10 cms of silt can be deposited. The last time desilting was done in our lakes was 10 years ago. Even then, only 2 of the 4 reservoirs were desisted. The Chembarambakkam lake was commissioned for desilting, but it was not done later," the officer confirmed to TNM, on the condition of anonymity.