Nexus of Good: With twin benefits

Given the water scarcity in many districts of Tamil Nadu, the state government has been laying special emphasis on rainwater conservation and harvesting. The conventional rainwater harvesting structures involve collection of rooftop rainwater and letting the water into a soak pit. This method ensures that the rainwater is not wasted and is let off into the ground, thus improving groundwater table.

Taking this rainwater harvesting process to the next level, the Dindigul district administration explored the feasibility of reusing the harvested rainwater before letting it off to the soak pit. A trial rainwater harvesting structure was constructed at three places with a provision to store and reuse the harvested rainwater. The rainwater collected on the rooftop was filtered using a filter media and then stored in a sump. The sump had an outlet that led to a nearby abandoned borewell or soak pit which was converted into a recharge structure. Thus, during the normal rains, the collected rainwater would be filtered and stored in the sump. During heavy rains, the excess water would flow from the sump through the outlet pipe into a nearby abandoned borewell or soak pit which could be converted into a recharge structure.

In this rainwater harvesting structure, the water collected on the rooftop is filtered using a filter media with various sizes of metal, and is then stored in a sump. The soak pit adjacent to the sump absorbs excess rainwater during heavy rains.

The Dindigul district administration planned to create a new world record by constructing such rainwater harvesting structures with storage capacity in multiple locations across the district. After elaborate planning, a scheme was formulated. It was decided to construct 611 such structures across the district in 21 days.

Applications were submitted to four agencies – Elite World Records, Asian Records Academy, India Records Academy and Tamilan Book of Records — that are engaged in recording such events/activities. This was to be recorded under the category 'Most Roof-Top Rainwater Harvesting Structures Constructed at Multiple Locations in 21 Days'. District administration selected 611 locations to execute this project across 306 village panchayats. The project was executed through the District Rural Development Agency. It was decided to select most of the primary and middle schools in Panchayat Union to ensure that they become self-sufficient with respect to water needs.

The work was started on November 10, 2021. Adjudicators from various world record agencies visited the sites earmarked for building rainwater harvesting structures. Various conditions put forth by these agencies had to be fulfilled. Prominent ones were as follows:

• The sump in which the rainwater was to be stored should have a minimum capacity of 9,000 litres.

• The sump should be constructed using bricks/plain cement concrete/reinforced cement concrete only. Plastic and fiber-reinforced plastic sumps were not accepted.

• There should mandatorily be a provision for excess rainwater to flow into either an abandoned bore well/open well or soak pit which is converted into a recharge structure.

• There should mandatorily be a gap of minimum five meters between the sump in which the rainwater is stored and the nearest septic tank.

With only 21 days available, and amid heavy rains forecast, the work was started simultaneously in all the 611 locations on November 10, 2021.

A detailed micro-level plan, incorporating material availability, skilled labour availability and a contingency plan (in case of heavy rains), was prepared. The capacity of the sump ranged from 9,000 litres to 27,000 litres, depending on the rooftop area of the building in which the structure was planned.

Work was carried out day and night to finish it within the scheduled 21 days. Out of the 21 available days, there was incessant rain for more than 10 days. Yet a committed and dedicated team worked tirelessly to finish the work within the stipulated time.

The total sump capacity built across 611 locations in these 21 days was 80 lakh litres. Thus, for a single rain, Dindigul district is now equipped to store 80 lakh litres of water for reuse.

A rainfall of one mm over an area of one square meter normally would provide one litre of water. The combined area of buildings taken up for constructing rainwater harvesting structures in Dindigul is 1,03,033 square meters. Dindigul district receives an average rainfall of 1,000 mm per year. Thus, the capacity to store and reuse rainwater in Dindigul district in a year would be 10.3 crore litres of water which is equivalent to the storage capacity of a small dam.

Recognising this feat, the aforementioned agencies conferred their world record certificates to the District Collector of Dindigul.

This just appears to be the beginning for a district that is planning to construct such structures in all private schools, hotels, marriage halls and commercial establishments in the coming future.

Water conservation is the need of the hour as more and more areas of the country are facing drinking water crises. Dindigul has demonstrated that this crisis can be handled locally. What has been made possible in Dindigul, presents a wonderful example of Nexus of Good. It is truly remarkable. The entire district team deserves to be complimented. What they have managed to achieve, holds lessons for all water-scarce districts in the country. Water-scarce areas can benefit from the Dindigul model by replicating it in their own districts.

Views expressed are personal