The average ground water level in the city rose by 0.80 metres due to implementation of rainwater harvesting, according to Chennai Metro Water.
A Chennai Metro Water report said the water level was 4.20 metre from the surface, but after the rain water harvesting, the water level had risen to the level of 3.20 metre from the surface.
The ground water levels in Tiruvotiyur, Manali, Madhavaram, Tondiarpet, Royapuram, Thiru-Vi-Ka Nagar, Ambattur, Anna Nagar, Teynampet, Kodambakkam, Valasaravakkam, Alandur, Adyar, Perungudi and Sholinganallur had improved the report said. The ground water level in Alandur which was 7.45 metres deep before monsoon rose to 4.80 metres due to rain water harvesting, it said. It also said the groundwater quality, which gives a measure of the total dissolved solids had also improved in the range of 500 to 1700 particles per cubic metre.
Interestingly, this comes after the city installed eight lakh rain water harvesting structures. Besides, the Chennai Metropolitan Development Authority plans to carry out rainwater harvesting audit though a network of NGOs, who pioneered in this field.
The biggest challenge for ground water depletion is heavy extraction of ground water. According to estimates, the city requires 1100 mld of water a day while Metro Water supplies around 830 MLD a day. As such nearly 300 mld of water is extracted from the ground.