HOW TO HARVEST IT WELL
WHERE YOU LIVE DICTATES THE BEST METHOD OF HARVESTING, BUT AIM TO MAXIMISE UTILITY AND RECHARGE GROUND TABLE
ARCHITECT Sai Prasad Renugunta, who is an expert on water harvesting pits, says that there are three types of pits: Rainwater harvesting; Direct storage for recharging borewells, suitable for small homes and apartments; and, injection wells which are best suited for apartments and gated communities.
RAINWATER harvesting pits are very difficult to build in existing buildings as they have to satisfy conditions like soil type, space availability, absorption capacity. For an individual house of 200 square yards, a 5x5x6 feet pit should be dug, depending on the soil condition. Most homes do not have this much space, and an alternative technique is storing rainwater and reusing it. This way residents can spend less on electricity and the quality of water is better.
FOR SMALL BUILDINGS, direct storage is efficient and doesn’t need much space. It can be built easily in existing buildings, and gives faster return on investment for people buying water from tankers. It recharges borewells directly, is more cost effective than harvesting pits. A 1,000-square-feet roof area generates around 50,000 to 60,000 litres per annum.
INJECTION WELLS work well for large areas and communities. A borewell is drilled and water is allowed to penetrate deeper cracks. This system not only improves the groundwater table but also improves the quality of water by diluting the salts. An estimate puts the number of water harvesting pits in the city at 4 lakh Space required to construct a pit: 5x5x6 feet
RAINWATER penetrates easily when the soil pattern is murram and not rocky or granite.
The pit should be constructed away from the pillars to avoid damage to the latter.
THE COST of an average water harvesting pit ranges between `9,000`11,000, depending on the size.
Even minor damage to concrete structures like pavement blocks, destruction of plants cost the municipal corporation. Renovation of a 100-sq m park costs the GHMC `2,500.