Rainwater harvesting by rainwater harvesting structures that uses a recharge shaft is an effective method to collect and store rainwater underground, thereby replenishing the groundwater levels. A recharge shaft is a vertical structure designed to direct rainwater from the surface to the underground aquifer.

The process involves selecting a suitable site for the recharge shaft, typically an open area with good exposure to rainfall and away from potential sources of contamination. Before constructing the shaft, a simple percolation test is conducted to assess the soil’s permeability, ensuring that it can effectively absorb and infiltrate the rainwater.

The recharge shaft is then drilled and a silting chamber is created around it by means of laying cement rings, filter media and perforated cement cover on top of the rings. This ensures the effective removal of silt and dirt from the runoff water and prevents sediment from clogging the shaft. To further filter the water, the recharge shaft/perforated pipe is wrapped with geotextile fabric/green shade net inside the siltation chamber.
KKPA has encouraged the public to install rainwater harvesting structures and completed rainwater harvesting structures with and without recharge shafts in 50 houses in Coimbatore.

The primary purpose of these rainwater harvesting structures is to recharge the groundwater levels. By directing rainwater into the underground aquifer, the recharge shaft augments the ground water resources and helps maintain a sustainable supply of groundwater, which is crucial for agriculture, drinking water, and industrial purposes. Following are the list of outcomes of the activity.

Overall, rainwater harvesting structure under the program with recharge shafts promote sustainable water management, help combat water scarcity, and contribute to a greener and more resilient environment. However, the effectiveness of the system depends on factors such as the amount of rainfall, soil characteristics, and proper maintenance of the infrastructure.