Percolation Ponds

These are the most prevalent structure to recharge groundwater reservoir in alluvial as well as in hard rock formations. Percolation pond be located a highly fractured and weathered rock for speedy recharge. In case of alluvium, the boulder formations are ideal for locating percolation pond. Design capacity should not be normally more than 50% of total quantum of rainfall in the catchment. Recharge wells with sitters are also constructed in the percolation pond.

Recharge Pit/Trench

These are the most efficient and cost effective structures to recharge the aquifer directly. In the areas where source of water is available either for some time or perennially (e.g) base flow, springs etc., the recharge shaft can be constructed. Recharge pits of size of minimum 1mx1mx1m or 1m diameter shall be provided wherever needed so as to prevent rain water stagnation around the building. For other places catch water pit structures of size 30 cm diameter and 30 cm depth or higher depth as necessary shall be provided at the bottom of the drains at 10 to 15 m intervals silted with appropriate material.

Gate Gutter Recharge wells

These are useful in areas where the entire surface area is covered with cement pavement. Gate Gutters helps in collecting all the water at the gate and recharge the underground. Normally 1 feet deep gutter filled with pebbles with a reinforced concrete slabs with holes of required length preferably to the length of the gate are need to be fixed at the gate.

Things to be remembered for RRWH/RWH

• The nature of Rainwater Harvesting (RWH) structures and their design parameters remain the same to any building except the physical scale (size) and number of structures, which may increase corresponding the size of the catchment.
• If man holes (waste water line) are present in the open spaces, the height of which have to be raised a little to avoid draining of rainwater along with wastewater.
• The cost of the rainwater harvesting structures may vary depending on the availability of the existing structures like wells / tanks, which may be modified to be used, thereby reduce the cost.
• Grill / mesh has to be fixed at the entrance/ mouth of the rainwater pipe in the terrace to filter large particles such as leaves etc.,
• For effective recharge to groundwater, combination of difference structures may be used as per the site requirements.
• All recharge structures must be properly maintained for effective recharge throughout the year.
• Maintenance is very easy and simple. The filter media should be properly cleaned, dust particles removed and backfilled during the non-rainy season.
• In the critical firkas, ground water should be utilized only for domestic purposes unless the groundwater is recharged substantially through artificial recharge techniques.
• Awareness on rainwater harvesting should start from panchayats school level and should be expanded to the entire community as a mass movement.

Existing Acts/Rules should follow

‘Right to Water’ is not explicitly covered in Article 21 of the Indian Constitution but under the broad rubric of ‘Right to Life’. Article 51A of our Constitution envisaged that it shall be the fundamental duty of every Indian citizen to protect and improve the natural environment, including forests, lakes, rivers and wildlife, and to have compassion for living creatures.

In order to conserve water resources, several water-related policies have been formulated. The National Water Policy (NWP) was first formulated in 1987 and updated and notified it in 2002 and in 2012, respectively. NWP is considered to be a comprehensive water policy that highlights NRW, water-efficient technologies, rainwater harvesting, reuse of treated water etc. It provides an overview of the water resource situation, addresses the problem because of its scarcity and suggests development with conjunctive use of surface and groundwater. The National Water Mission (NWM), launched under the National Action Plan on Climate Change (NAPCC), recommends 20 per cent water-use efficiency programmes, including water conservation and water recycling. Subsequently, the state of Tamil Nadu has also prepared draft state water policy with reference to NWP for water management.

The ‘Water Act and Environmental Act’ 1996 should be amended to give provision for rainwater harvesting and to ban the diversion of natural flow of rainwater by encroachments on streams and ‘odaiporomboke’. The recent judgment of the Supreme Court against filling up of tanks and building houses should be implemented.