Water is an essential commodity for many industrial units and commercial establishments, and its availability in adequate quantity and quality is crucial to their existence. One cannot even remotely imagine the existence of industries like Textiles, Paper, Engineering, and Chemical, and sectors like Housing, Hospitality and Healthcare, without water. Of the various sources of water, it is ground water that provides a sizeable amount to the industrial and commercial sectors. Dependence on ground water has been ever increasing for the many advantages it offers. It is available wherever and whenever it is required. It is of a more uniform character and relatively free from harmful bacteria. This resource can be developed at a small capital cost and in a short time. However, with the increasing use of ground water for agricultural, municipal, industrial and commercial needs, its annual extraction has become far in excess of the net average recharge from natural sources. The opportunity for the natural recharge of ground water aquifers has got diminished due to the construction of more buildings, roads, parking lots and airports, which cater to the rapid growth in population and urbanisation. The resulting massive concretisation has lead to the sealing of many natural recharge channels. The large-scale plantation of many Eucalyptus trees a couple of decades ago has also added to the depletion of ground water. Traditionally, the village johar-cum-oxidation ponds have been used for the recharge of underground aquifers. The process of natural percolation, through layers of soil and rocks, provided for the filtration of impurities and pollutants before the recharge water could reach the ground water source. Rapid urbanisation has led to the encroachment on natural water bodies – thus reducing the opportunities for the natural recharge of ground water.
The solution to the problem of fast declining ground water levels lies in augmenting the natural infiltration of rain water into underground formations by a method of construction commonly termed as Artificial Recharge. Artificial Recharge by bore wells allows the recharge water to go straight to the underground aquifers. However, this means that the quality of recharge water must be very good. If this recharge water contains any impurities or pollutants, they will get mixed with the underground water resource. Almost every industrial and commercial establishment makes use of some sort of material for its operations. Despite good housekeeping, some of these materials find their way onto the floors and driveways. Some industrial units discharge liquid effluents. When it rains, some of these materials get mixed with the rain water. This polluted water is not fit for the recharging of ground water and must not be allowed into a rain water harvesting system. However, rain water from roof tops of buildings is ‘safe’ water for the recharge of ground water. Even the Central Ground Water Authority talks of only a Roof Top Rain Water harvesting (RTRWH) system. The process of RTRWH is a systematic channelisation of the rain falling on the roof tops of buildings and directing the same to collection tank(s), which has/have the required bore well(s). Each tank is charged with a filter media. It is usually covered from the top. The shape may be rectangular, square or circular, depending on the site. The recharge tank is sized for at least one hour of run-off. In case of a large roof top area, multiple tanks are planned at suitable locations in the premises. The filter media in tank(s) needs to be cleaned after every rainy season, or the whole system may become ineffective.
Rain water is a natural source of good quality water and needs to be protected, conserved and used for the benefit of mankind. Great care is required in planning and designing the system of Artificial Recharge. It should be such that: no water other than rain water from the roof tops of buildings finds its way into the ground water; no treated/partially treated/untreated effluent is disposed off in the rain water harvesting structure, specially in un-sewered areas; adequate recharge capacity is created to harvest all water available from the roof tops. The system should be periodically cleaned. Sincere efforts by everyone connected with water, specially industry and trade, will contribute significantly in conserving the fast-depleting resource of ground water.
Chairman, Committee forEnvironment & Pollution Control, NCR Chamber of Commerce and Industry, Gurgaon (views expressed are personal)