The water bodies in Chennai, which recently ran bone dry, are almost up to the brim today, thanks to an excellent start to the northeast monsoon. But has the city made optimal use of this opportunity, to ensure that it does not face the kind of water crisis that it saw earlier this year? Probably not.
The state of our roads, which begin to resemble water bodies after even a brief spell of intense rain, is just one indicator of the poor state of water harvesting and storage in the city. Rainwater Harvesting (RWH) structures in Chennai date back to 2001, when the then Chief Minister J Jayalalithaa pushed for amendments to Section 215 (a) of the Tamil Nadu District Municipalities Act, 1920 and Building Rules 1973, and made it mandatory for all new buildings to install such facilities.
Compliance with the new rules was commendable. “It was a perfect match of political will and executive competence in Tamil Nadu that made RWH possible. Everyone from civil society, the judiciary and executive participated and promoted it. We did not have to impose penalties on even a single case. It has not been replicated in any other part of the country,” recalls Santha Sheela Nair, former Municipal Administration and Water Supply (MAWS) Secretary who had taken a strong stance on RWH.
Ironically, sixteen years after the law was implemented, the state lags behind in upgrading its RWH infrastructure, which would enable it to harvest water in a scientific manner. RWH structures in many government buildings are perfunctory. According to recent statistics obtained from the Public Works Department, 96 per cent of the buildings in Tamil Nadu have harvesting facilities, while the small balance are either under repair or possess no structures. In Chennai, a total of 2,401 government buildings, of the total 2,488 ones, are said to be compliant( 96.5 per cent).
A quick field visit to a few government buildings in Chennai shows that there are multiple loopholes in the procedure of RWH, and the efficiency of the procedures leaves much to be desired.
Government buildings follow outdated RWH rules
Many of the buildings are still following outdated procedures that were framed when RWH was in a nascent stage, though researchers have come up with many more effective ones since.
For example, the trench area at the newly constructed Goods and Services Tax office near Anna Nagar terminus is filled with pebbles. But, there is no recharge well near the entrance to save the run-off water.
“Usage of pebbles can get the trenches silted easily, thus restricting the water percolation. A recharge well without a filter medium is the best option as soil can facilitate natural filtration. All we need to do is to bypass the soil media and recharge the aquifers,” said G Sundar Rajan of Poovulagin Nanbargal, a Chennai-based environmental organisation.
Another old practice is that bricks have been used as the filter medium in recharge wells. Experts say that the bricks, which become clay within months, block the water from percolation.
A similar scenario prevails at the Institute of Child Health and Hospital for Children in Egmore. The hospital, which draws around 50,000 litres every day from groundwater sources has harvested rain water from about 80 per cent of its area, both on the rooftop and in the setback area, according to the assistant engineer from the Public Works Department. There are a total of 24 recharge wells in the premises and another ten are being constructed now.
The trench at the Institute of Child Health and Hospital for Children, Egmore is filled with gravel.
But there is clearly no recharge well near the entrance of the hospital, due to which Halls Road gets flooded, even with a short spell of rain. In the setback area, the trench is filled with pebbles.
The hospital can meet one third of its total water demand if the premises are fully harvested, say authorities. “We require at least 240,000 litres each day. If we harvest the remaining area in the hospital, we can expect 70,000 litres from open and borewells every day,” said R S Raghunathan, the hospital’s Regional Medical Officer.
The Public Works Department (PWD), which is responsible for the maintenance of rainwater harvesting structures, is not at fault as they are merely complying with the law that emerged in 2003. But despite various suggestions from members of the scientific community, the government has not adopted the new RWH policy.
Lapses are mounting in the buildings that are not maintained by the PWD, including the offices of the Tamil Nadu Slum Development Board, Transport Department and Tamil Nadu Housing Board.
The office of Chennai Metro Water, located on the floodplains of Buckingham canal in Chintadripet, has also adopted the pebble stone trench approach, connected to recharge wells. However, officials say that the pebbles are cleaned of silt before the onset of every monsoon. (If the pebbles had not been added at all, a significant amount of funds from the exchequer could have been saved).
New rules on RWH still on paper
A set of recommendations proposed by water experts, following an audit for the Chennai Metropolitan Development Authority in 2014, remains unapproved on the table of the Ministry of Housing and Urban Development.
The audit conducted by the Akash Ganga Trust to strengthen and streamline RWH proposed many corrective measures, in order to maintain sustainable water resource management in the Chennai Metropolitan Area. The survey, which categorized the soil in the city into three types – sandy, clayey and hard rock terrain – reiterated the need to adopt a RWH structure on the basis of the particular soil type.
For easy understanding, areas closer to the coast such as Besant Nagar and Thiruvotriyur comes under the sandy zone, whereas localities like Ambattur and Porur are in the clayey region. Localities with mountains, including Velachery and Tambaram, are in the hard rock terrain.
Sekhar Raghavan, conservation expert and director of Chennai-based Rain Centre says, “It is necessary to adopt an RWH structure that is suitable for the soil type in the area. In a hard rock surface, you can store the water in sumps as recharge is not possible. In a clayey region, if it doesn’t turn sandy beyond 15 feet, we can dig up a small hole within a recharge well and insert a pipeline of six inches that takes the water to a deeper layer. A well of 3 feet to 5 feet diameter would suffice in sandy regions.”
“Many rainwater harvesting structures in Tamil Nadu are constructed without paying heed to the nature of the soil. Even among the well constructed ones, maintenance is not adequate. As a result, we still have a lot of untapped potential for RWH,” admits a senior government official.
Recommendations for improvement
The survey mentioned above noted several interesting facts about the current infrastructure in place. Sekhar, who is a part of the team, said that a majority of the government buildings focused on harvesting water from the rooftop and not the setback area, despite the 2003 RWH rules mandating it.
“It should be noted that in sandy coastal areas, leaving the open areas unpaved would itself result in percolation of surface runoff and recharge to groundwater. But , the surface area has been paved and the surface runoff is not being harvested. This will result in simple runoff and flooding on the roads or diversion into the public storm water drains,” notes the survey, a copy of which is with Citizen Matters.
According to the survey, structured training programmes, highlighting the importance of designing subsoil-based recharge systems, should be created for plumbers, masons, engineers and contractors, who play a major role in design and implementation of effective RWH systems.
Other important recommendations include:
- Setting up a Department for Rainwater Management
- Setting up a RWH Cell in Chennai Metrowater Supply and Sewerage Board
- Issuance of Completion certificates by Greater Chennai Corporation
- Third party monitoring of completed projects
- Water tariff with slab rates (similar to electricity metering)
- Conjunctive use of aquifers
- Handover of relevant reports to Resident Welfare Associations by builders