Kerala has 70 lakh wells, according to a study conducted by the Centre for Water Resources Development and Management in 2005-06. There are 76.5 lakh ‘occupied houses used as residence’, as per the 2011 census. It would mean that there is almost enough number of wells to cater to the water needs of residences. Yet, water supply is woefully inadequate across the length and breadth of Kerala.
Prior to the arrival of piped water to dwelling units, most people depended on wells and ponds for drinking water. But many of the wells have been discarded in the aftermath of access to protected water supply. The water scarcity arising out of the vagaries of the monsoon and pollution problems have necessitated a new look at the water availability in urban areas.
With a receding groundwater table, rainwater harvesting has been made mandatory for new buildings, aimed at recharging the water resources. The government had made it mandatory to set up rainwater harvesting facilities by means of Municipality Building (Amendment) Rules, 2004. Accordingly, workable rooftop rainwater harvesting arrangements should be provided as an integral part of all new buildings for residential purposed with a floor area of 100 sq.m or more and plot area of 200 sq.m or more; educational institutions; hospitals, offices and industrial workshops assembly plants, dairies , refineries, food processing units and any other occupancies notified by the government.
“The rule on rainwater harvesting is not being implemented strictly”, observes Robert G.Thomas, Ernakulam regional engineer of Nirmithi Kendra, entrusted with the task of providing consultancy for rainwater harvesting. Only about 30 per cent of houses in Kochi have rainwater harvesting facilities at present. New houses are having the facility but very few people take care to install the system in those ones having no harvesting facility.
The wells in coastal belt are comparatively more polluted, says D.B.Narasimha Prasad, head of Ground Water Division of CWRDM, Kozhikkode, pointing out the need for recharging of well water. “Eighty-five per cent of the annual rainfall in Kerala is received during a six-month period between June and November, leaving the remaining six months almost dry months. The undulating and steep land slope from east to west makes the rainfall to runoff fast in to the Arabian Sea. Hence, there is less time for recharge to take place. Due to these natural peculiarities of Kerala, groundwater becomes a very important perennial water resource,” Mr.Prasad says.
“The ground water potential of Kerala is very low as compared to that of many other States in the country,” says P.S.Harikumar, head of Water Quality Division of the CWRDM. The open well density in Kerala is perhaps the highest in the country – 200 wells per sq.km in the coastal region, 150 wells per sq.km in the midland and 70 wells per sq.km in the high lands, according to a study made by his department. The depth of the water level in the State varies from few cm bgl (below ground level) to 56 m. bgl and most of the area falls under 0-20 m bgl,” he says.