After its intensive campaign to popularise rainwater harvesting, Rain Centre is now promoting recycling of grey water in residential complexes using a natural and economical method.

For the past eight months, the voluntary organisation has been helping residents across the city recycle the water used for washing and bathing purposes or recharge groundwater. A simple treatment process using canna plants (‘Kalvazhai' in Tamil) was implemented in many residential complexes to filter the waste water.

The grey water is passed through the canna bed, which is created over layers of blue metal and soil. The canna plants help in decomposition of the suspended solids. The soil layer beneath filters the water. A collection pit is constructed to prevent percolation of the filtered water, which, in turn, is pumped to the overhead tank. A separate partition is made in the overhead tank for storing the water. A.Sanjeevi, resident of Sarvamangala Nagar, Nanganallur, said: “We have adopted the method to both recharge groundwater and re-use part of the treated waste water for flushing and gardening purposes. We recover about 500 litres of water from the process daily. A minimum of 60 square feet of area and moderate sunlight are required for the treatment.”

V.S. Sukumar, a resident of Gandhi Nagar, Adyar, said water level in the shallow well on the premises has not gone dry after the treatment process was implemented for recharging groundwater a year ago. Rain Centre director Sekhar Raghavan said besides rainwater harvesting, recycling waste water is also important for efficient water management. Adopting this low-cost method would recycle at least 50 per cent of the water discharged in to sewerage network. “There are plans to conduct awareness programmes for builders. We are planning to approach Chennai Metrowater to conduct seminars for consumers to create awareness of grey water recycling as was done for RWH,” he said. The Centre also has a team to help residents implement the treatment process. Indukanth Ragade, an organic expert, has been providing expertise to the centre to implement waste water recycling in residential complexes. “There is no mosquito breeding or stench from the canna beds as water is absorbed quickly. However, it needs periodical maintenance. The plants must be removed once it flowers to allow fresh plants to grow,” he said.