Safe drinking water is a pre-requisite for development of any society. All the known civilizations have flourished with water source as the base and it is true in the present context too. Availability of safe drinking water is one of the basic minimum requirements for healthy living. Despite the advancements of technology in recent pasts, the global scenario still remains grim, as all the inhabitants of the world do not have access to safe water.
In the face of increasing scarcity of water resources, there is a need for every user to think about the possible solution to cope with the crisis. Like many other developing countries, public water supply in Bangladesh evidently provides a shortfall in demand. Towards sustainable management of freshwater with respect to the physical alternatives, the possible solutions could be finding alternate or additional water resources using conventional centralized approaches; or utilizing the limited amount of water resources available in a more efficient way.
Among the various technologies to augment freshwater resources in order to reduce the scarcity of safe water, Rainwater Harvesting and its utilization could be an environmentally sound solution, which can avoid many environmental problems often caused by conventional large-scale projects using centralized approaches.
Rainwater is an important water source in many areas with significant rainfall like Bangladesh. It is also a good option in areas where good quality fresh surface water or ground water is lacking or difficult to avail. It is said that nature's renewable sources will probably never end. But these resources are not usually explored enough to mitigate the crisis. Rainwater is one of those resources available from nature which is abundant in almost all parts of Bangladesh.
Rainwater harvesting, in its broadest sense, is a technology used for collecting and storing rainwater for human use from rooftops, land surfaces or rock catchments using simple techniques such as jars and pots as well as engineered techniques.
Rainwater harvesting is a good alternative in areas where there is sufficient rain but the ground water supply and surface water resources are either lacking or insufficient. It could also be thought as a long term answer to the problem of water scarcity. Rainwater harvesting system is particularly useful in remote and hard-to-reach areas as it can be maintained independently.
There are a number of ways in which water harvesting can benefit a community –
- Rainwater harvesting enables efficient collection and storage of rainwater makes it accessible and substitutes for poor quality water.
- While traditional sources are located away from the community particularly in peri-urban areas, collecting and storing water close to households, villages or pastures greatly enhances the accessibility and convenience of water supplies.
- The rainwater collected can be stored for direct use or can be recharged into the ground water to improve the quality of ground water.
- Rainwater harvesting is an ideal solution to water problems in areas having inadequate water resources and helpful in mitigation of the effects of drought.
Rainwater is also the cheapest form of raw water. The rainwater harvesting systems can be both individual and community/utility operated and managed. Rainwater collected using various methods has less negative environmental impacts compared to other technologies for water resources development. The physical and chemical properties of rainwater are usually superior to sources of ground water that may have been subjected to contamination. Rainwater is relatively clean and the quality is usually acceptable for many purposes with little or even no treatment. Rainwater harvesting technologies are flexible and can be built to meet almost any requirements. Construction, operation, and maintenance are not labor intensive. The role of rainwater harvesting systems as sources of supplementary, back-up, or emergency water supply will become more important especially in view of increased climate variability and the possibility of greater frequencies of droughts and floods in many areas. This will particularly be the case in areas where increasing pressure is put on existing water resources.
Groundwater has now become a major natural resource contributing the water supply system in many areas of Bangladesh, especially in Dhaka. Due to urbanization, surface infiltration has been vastly reduced while consumption of groundwater is increasing. In addition, the over exploitation through excessive extraction of groundwater have been exceeding its replenishment capacity. This has lead to searching for deeper aquifers and making the whole process more costly. As surface water is very costly and inadequate to meet our demand in many places and due to rapid urbanization, infiltration of rainwater into the sub-soil has decreased drastically, artificial recharge through rainwater harvesting is essential to replenish the groundwater. The mechanism is very simple and requires little space. Artificial recharge to ground water is a process by which the groundwater reservoir is augmented at a rate exceeding that obtaining under natural conditions of replenishment.
In addition to its potential to generate considerable quantities of water, rainwater harvesting results in a process of collecting water that is decentralized and therefore, relatively less vulnerable than conventional public water supplies to natural disasters. Another advantage of rainwater harvesting is that its systems are generally cost-competitive with well drilling and it provides water that is naturally soft, eliminating the need for water softeners. Considering the adaptive capability and available resources, rainwater harvesting can be considered as a sustainable option in water resource management.